/* =====================================================================
   Landing page (index.html) and the legal pages. Builds on the tokens and
   buttons in style.css + shell.css; everything here is prefixed lp-/sim-.
   ===================================================================== */

body.lp {
  background: var(--bg);
  overflow-x: hidden;
}
/* shell.css styles the app's #main as a panel; the landing page has none */
.lp #main {
  background: none;
  border: 0;
  border-radius: 0;
  min-height: 0;
}
.skip-link {
  position: absolute;
  left: -999px;
  top: 8px;
  z-index: 100;
  background: var(--panel);
  padding: 8px 14px;
  border-radius: 8px;
  border: 1px solid var(--border);
}
.skip-link:focus {
  left: 8px;
}
.lp-wrap {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 24px;
}
.lp h1,
.lp h2,
.lp h3 {
  letter-spacing: -0.02em;
}
.lp .btn.big {
  padding: 12px 20px;
}
.lp .btn svg {
  flex: none;
}
.glyph-emoji {
  font-size: 0.95em;
}

/* ------------------------------------------------------------ nav */
.lp-nav {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid transparent;
  transition: background 0.2s, border-color 0.2s;
}
.lp-nav.scrolled,
.lp-nav.menu-open {
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: saturate(140%) blur(14px);
  -webkit-backdrop-filter: saturate(140%) blur(14px);
  border-bottom-color: var(--border);
}
.lp-nav-inner {
  display: flex;
  align-items: center;
  gap: 28px;
  height: 64px;
}
.lp-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  text-decoration: none;
  font-weight: 600;
  font-size: 15.5px;
  letter-spacing: -0.01em;
  white-space: nowrap;
}
.lp-brand b {
  color: var(--accent);
  font-weight: 700;
}
.lp-brand img {
  display: block;
  border-radius: 8px;
}
.lp-links {
  display: flex;
  gap: 4px;
  flex: 1;
}
.lp-links a {
  white-space: nowrap;
}
.lp-links a,
.lp-mobile a {
  color: var(--muted);
  text-decoration: none;
  font-size: 14.5px;
  font-weight: 500;
  padding: 6px 10px;
  border-radius: 8px;
  transition: color 0.15s, background 0.15s;
}
.lp-links a:hover {
  color: var(--text);
  background: color-mix(in srgb, var(--text) 6%, transparent);
}
.lp-nav-cta {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: auto;
}
.lp .icon-btn {
  display: inline-grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 9px;
  border: 1px solid transparent;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
}
.lp .icon-btn:hover {
  color: var(--text);
  background: color-mix(in srgb, var(--text) 6%, transparent);
}
.lp-menu {
  display: none !important;
}
.lp-mobile {
  display: flex;
  flex-direction: column;
  padding: 8px 16px 16px;
  border-top: 1px solid var(--border);
}
.lp-mobile[hidden] {
  display: none;
}
.lp-mobile a {
  padding: 12px 8px;
  font-size: 16px;
  color: var(--text);
  border-bottom: 1px solid var(--border);
  border-radius: 0;
}
.lp-mobile .btn.primary {
  margin-top: 14px;
  justify-content: center;
  color: var(--btn-primary-ink, #fff);
  border: 0;
  border-radius: 12px;
}

/* ------------------------------------------------------------ hero */
.lp-hero {
  position: relative;
  padding: 56px 0 72px;
}
.lp-hero::before {
  content: "";
  position: absolute;
  inset: -64px 0 0;
  z-index: -1;
  background-image: linear-gradient(color-mix(in srgb, var(--text) 5%, transparent) 1px, transparent 1px),
    linear-gradient(90deg, color-mix(in srgb, var(--text) 5%, transparent) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse 80% 70% at 50% 20%, #000 30%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse 80% 70% at 50% 20%, #000 30%, transparent 75%);
}
.lp-hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 0.92fr) minmax(0, 1.08fr);
  gap: 48px;
  align-items: center;
}
.lp-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 12px 5px 10px;
  border-radius: 99px;
  border: 1px solid var(--border-strong);
  background: var(--panel);
  color: var(--text);
  font-size: 13px;
  font-weight: 500;
  text-decoration: none;
}
.lp-eyebrow:hover {
  border-color: color-mix(in srgb, var(--accent) 50%, var(--border));
}
.live-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--ok);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--ok) 22%, transparent);
  flex: none;
}
.lp-hero h1 {
  font-size: clamp(38px, 4.4vw, 58px);
  line-height: 1.05;
  letter-spacing: -0.038em;
  font-weight: 800;
  margin: 22px 0 18px;
  text-wrap: balance;
}
.lp-hero h1 .hl {
  color: var(--accent);
}
.lp-lead {
  font-size: 18px;
  line-height: 1.6;
  color: var(--muted);
  margin: 0 0 28px;
  max-width: 540px;
}
.lp-cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
.lp-cta-row.center {
  justify-content: center;
}
.lp-proof {
  list-style: none;
  padding: 0;
  margin: 26px 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  font-size: 13.5px;
  color: var(--muted);
}
.lp-proof li {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.lp-proof .glyph {
  color: var(--ok);
  width: 16px;
  height: 16px;
}

/* ------------------------------------------------------------ hero simulation */
.lp-sim {
  background: var(--panel);
  border: 1px solid var(--border-strong);
  border-radius: 18px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}
.sim-top {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 11px 14px;
  border-bottom: 1px solid var(--border);
  background: var(--panel-2);
}
.sim-dots {
  display: flex;
  gap: 6px;
}
.sim-dots i {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--border-strong);
}
.sim-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--muted);
  flex: 1;
}
.sim-mode {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 12px;
  font-weight: 600;
  color: var(--muted);
}
.sim-metrics {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border-bottom: 1px solid var(--border);
}
.sim-metric {
  padding: 10px 14px;
  border-right: 1px solid var(--border);
  min-width: 0;
}
.sim-metric:last-child {
  border-right: 0;
}
.sim-metric span {
  display: block;
  font-size: 11.5px;
  color: var(--muted);
  white-space: nowrap;
}
.sim-metric b {
  display: block;
  font-size: 19px;
  font-weight: 700;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
  transition: color 0.3s;
}
.sim-metric[data-level="warn"] b {
  color: var(--warn);
}
.sim-metric[data-level="bad"] b {
  color: var(--bad);
}
.sim-stage {
  background-color: var(--bg-2);
  background-image: radial-gradient(color-mix(in srgb, var(--muted) 20%, transparent) 1px, transparent 1px);
  background-size: 20px 20px;
}
.sim-svg {
  display: block;
  width: 100%;
  height: auto;
  font-family: Inter, system-ui, sans-serif;
}
.sim-edge {
  stroke: var(--border-strong);
  stroke-width: 1.6;
  transition: stroke 0.3s, opacity 0.3s;
}
.sim-edge.down {
  stroke: var(--bad);
  stroke-dasharray: 4 6;
  opacity: 0.6;
}
.sim-edge.off {
  opacity: 0.25;
  stroke-dasharray: 4 6;
}
.sim-packet {
  stroke: var(--bg-2);
  stroke-width: 1.5;
}
.sim-box {
  fill: color-mix(in srgb, var(--k) 12%, var(--panel));
  stroke: color-mix(in srgb, var(--k) 75%, var(--border));
  stroke-width: 1.6;
  transition: fill 0.3s, stroke 0.3s;
}
.sim-label {
  fill: var(--text);
  font-size: 12.5px;
  font-weight: 650;
}
.sim-sub {
  fill: var(--muted);
  font-size: 11px;
  font-variant-numeric: tabular-nums;
}
.sim-node .node-glyph {
  transition: stroke 0.3s, opacity 0.3s;
}
.sim-node.down {
  opacity: 0.55;
}
.sim-node.down .sim-box {
  stroke: var(--bad);
  stroke-dasharray: 5 4;
  fill: color-mix(in srgb, var(--bad) 10%, var(--panel));
}
.sim-node.down .node-glyph,
.sim-node.hot .node-glyph {
  stroke: var(--bad);
}
.sim-node.down .sim-sub {
  fill: var(--bad);
}
.sim-node.off {
  opacity: 0.4;
}
.sim-node.busy .sim-box {
  stroke: var(--warn);
  fill: color-mix(in srgb, var(--warn) 14%, var(--panel));
}
.sim-node.hot .sim-box {
  stroke: var(--bad);
  fill: color-mix(in srgb, var(--bad) 18%, var(--panel));
  animation: sim-hot 0.9s ease-in-out infinite alternate;
}
.sim-node.hot .sim-sub {
  fill: var(--bad);
  font-weight: 700;
}
@keyframes sim-hot {
  to {
    fill: color-mix(in srgb, var(--bad) 30%, var(--panel));
  }
}
.sim-say {
  margin: 0;
  min-height: 66px;
  padding: 12px 16px;
  font-size: 14.5px;
  line-height: 1.5;
  border-top: 1px solid var(--border);
}
.sim-say.fade {
  animation: fadeUp 0.35s ease;
}
.sim-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  padding: 0 16px 14px;
}
.sim-try {
  font-size: 12.5px;
  font-weight: 600;
  color: var(--muted);
  margin-right: 2px;
}
.sim-controls .btn[aria-pressed="true"] {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-soft);
}
.lp-textbtn {
  border: 0;
  background: none;
  color: var(--accent);
  font: 600 13px Inter, system-ui, sans-serif;
  cursor: pointer;
  padding: 4px 6px;
  margin-left: auto;
}

/* ------------------------------------------------------------ stats */
.lp-stats {
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}
.lp-stats-row {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
}
.lp-stats-row > div {
  padding: 22px 12px;
  text-align: center;
  border-right: 1px solid var(--border);
}
.lp-stats-row > div:last-child {
  border-right: 0;
}
.lp-stats b {
  display: block;
  font-size: 30px;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.15;
}
.lp-stats span {
  font-size: 13px;
  color: var(--muted);
}

/* ------------------------------------------------------------ sections */
/* nav links land with the heading just under the sticky bar (the app's
   scroll padding doesn't apply here) */
html:has(body.lp) {
  scroll-padding-top: 0;
}
.lp-section {
  padding: 96px 0;
  scroll-margin-top: -16px;
}
.lp-section + .lp-section {
  border-top: 1px solid var(--border);
}
.lp-head {
  max-width: 720px;
  margin: 0 auto 48px;
  text-align: center;
}
.lp-head.left {
  text-align: left;
  margin: 0;
}
.lp-kicker {
  display: inline-block;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 12px;
}
.lp-head h2 {
  font-size: clamp(30px, 3.6vw, 44px);
  line-height: 1.12;
  letter-spacing: -0.03em;
  font-weight: 750;
  margin: 0 0 14px;
  text-wrap: balance;
}
.lp-head p {
  font-size: 17px;
  color: var(--muted);
  margin: 0;
}

/* how it works */
.lp-steps {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  counter-reset: step;
}
.lp-steps li {
  position: relative;
  padding: 26px 24px 24px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--panel);
}
.step-n {
  display: inline-grid;
  place-items: center;
  width: 32px;
  height: 32px;
  border-radius: 10px;
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 800;
  font-size: 15px;
}
.lp-steps h3 {
  font-size: 19px;
  margin: 16px 0 8px;
}
.lp-steps p {
  color: var(--muted);
  font-size: 15px;
  margin: 0 0 16px;
}
.step-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.step-tags span {
  font-size: 12px;
  font-weight: 600;
  padding: 3px 9px;
  border-radius: 99px;
  border: 1px solid var(--border-strong);
  color: var(--muted);
}

/* try a lesson */
.lp-demo {
  border: 1px solid var(--border-strong);
  border-radius: 18px;
  background: var(--panel);
  overflow: hidden;
}
.lp-demo-tabs {
  display: flex;
  gap: 4px;
  padding: 8px;
  border-bottom: 1px solid var(--border);
  background: var(--panel-2);
  overflow-x: auto;
}
.lp-demo-tabs button {
  border: 1px solid transparent;
  background: transparent;
  color: var(--muted);
  font: 600 14px Inter, system-ui, sans-serif;
  padding: 8px 14px;
  border-radius: 9px;
  cursor: pointer;
  white-space: nowrap;
}
.lp-demo-tabs button:hover {
  color: var(--text);
}
.lp-demo-tabs button[aria-selected="true"] {
  color: var(--text);
  background: var(--panel);
  border-color: var(--border-strong);
}
.lp-demo-body {
  display: grid;
  grid-template-columns: minmax(0, 0.7fr) minmax(0, 1.3fr);
}
.lp-demo-copy {
  padding: 26px 26px 24px;
  border-right: 1px solid var(--border);
}
.lp-demo-meta {
  font-size: 12.5px;
  font-weight: 600;
  color: var(--accent);
}
.lp-demo-copy h3 {
  font-size: 22px;
  margin: 6px 0 10px;
}
.lp-demo-copy .prose {
  font-size: 14.5px;
  line-height: 1.6;
  color: var(--muted);
  margin-bottom: 18px;
}
.lp-demo-copy .prose b {
  color: var(--text);
}
.lp-demo-copy .prose ul {
  padding-left: 18px;
}
.lp-demo-stage {
  padding: 18px;
  min-height: 420px;
}
.lp-demo-loading {
  color: var(--muted);
  font-size: 14px;
  display: grid;
  place-items: center;
  min-height: 380px;
  margin: 0;
}

/* ------------------------------------------------------------ bento */
.bento {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}
.tile {
  display: flex;
  flex-direction: column;
  gap: 18px;
  padding: 24px;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: var(--panel);
  min-width: 0;
  overflow: hidden;
}
.tile.span-2 {
  grid-column: span 2;
}
.tile-kicker {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
}
.tile h3 {
  font-size: 20px;
  margin: 8px 0 6px;
  line-height: 1.25;
}
.tile p {
  color: var(--muted);
  font-size: 14.5px;
  margin: 0;
}

/* simulator mock */
.tile-sim .tile-copy {
  max-width: 620px;
}
.mock-sim {
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(0, 1fr);
  gap: 14px;
  align-items: stretch;
  flex: 1; /* fill the tile when its neighbour is taller */
}
.mock-canvas {
  border: 1px solid var(--border);
  border-radius: 12px;
  background-color: var(--bg-2);
  background-image: radial-gradient(color-mix(in srgb, var(--muted) 18%, transparent) 1px, transparent 1px);
  background-size: 16px 16px;
  display: grid;
  align-items: center;
}
.mock-canvas svg {
  display: block;
  width: 100%;
  height: auto;
  font-family: Inter, system-ui, sans-serif;
}
.mc-edge {
  stroke: var(--border-strong);
  stroke-width: 1.4;
  fill: none;
}
.mc-edge.async {
  stroke-dasharray: 4 4;
}
.mc-arrow {
  fill: var(--border-strong);
}
.mc-box {
  fill: color-mix(in srgb, var(--k) 12%, var(--panel));
  stroke: color-mix(in srgb, var(--k) 70%, var(--border));
  stroke-width: 1.3;
}
.mc-label {
  fill: var(--text);
  font-size: 11px;
  font-weight: 600;
}
.mock-score {
  padding: 14px;
  border-radius: 12px;
  border: 1px solid var(--border-strong);
  background: var(--panel-2);
}
.ms-ring,
.md-ring {
  --c: var(--ok);
  width: 64px;
  height: 64px;
  border-radius: 50%;
  display: grid;
  place-content: center;
  text-align: center;
  background: radial-gradient(closest-side, var(--panel-2) 78%, transparent 80% 100%), conic-gradient(var(--c) calc(var(--v) * 1%), var(--border) 0);
  flex: none;
}
.ms-top {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 12px;
}
.ms-top b {
  display: block;
  font-size: 16px;
}
.ms-top span {
  font-size: 12px;
  color: var(--muted);
}
.ms-ring b,
.md-ring b {
  font-size: 19px;
  line-height: 1;
}
.ms-ring span,
.md-ring span {
  font-size: 10px;
  color: var(--muted);
}
.mock-score ul {
  list-style: none;
  padding: 0;
  margin: 0;
  font-size: 12px;
  line-height: 1.45;
}
.mock-score li {
  padding-left: 16px;
  position: relative;
}
.mock-score li::before {
  position: absolute;
  left: 0;
  font-weight: 800;
}
.mock-score li.ok::before {
  content: "✓";
  color: var(--ok);
}
.mock-score li.miss::before {
  content: "!";
  color: var(--warn);
  left: 3px;
}
.ms-follow {
  margin: 10px 0 0 !important;
  padding-top: 10px;
  border-top: 1px solid var(--border);
  font-size: 12px !important;
  color: var(--text) !important;
}

/* mini quiz */
.mini-q {
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px;
  background: var(--panel-2);
}
.mq-q {
  font-size: 14px !important;
  font-weight: 600;
  color: var(--text) !important;
  margin: 0 0 10px !important;
}
.mq-opts {
  display: grid;
  gap: 6px;
}
.mq-opts button {
  text-align: left;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  border-radius: 9px;
  padding: 8px 11px;
  font: 500 13.5px Inter, system-ui, sans-serif;
  cursor: pointer;
  transition: border-color 0.15s;
}
.mq-opts button:hover:not(:disabled) {
  border-color: var(--accent);
}
.mq-opts button:disabled {
  cursor: default;
}
.mq-opts button.right {
  border-color: var(--ok);
  background: color-mix(in srgb, var(--ok) 12%, var(--panel));
}
.mq-opts button.right::after {
  content: " ✓";
  color: var(--ok);
  font-weight: 800;
}
.mq-opts button.wrong {
  border-color: var(--bad);
  background: color-mix(in srgb, var(--bad) 10%, var(--panel));
}
.mq-why {
  margin: 10px 0 0 !important;
  font-size: 13px !important;
}

/* code mock */
.mock-code {
  margin: 0;
  padding: 14px 16px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--code-bg);
  font: 12.5px/1.6 "JetBrains Mono", ui-monospace, monospace;
  overflow: hidden;
  white-space: pre;
}
.mock-code .k {
  color: var(--tok-k);
}
.mock-code .f {
  color: var(--tok-f);
}
.mock-code .n {
  color: var(--tok-n);
}
.mock-pass {
  display: block;
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px solid var(--border);
  color: var(--ok);
  font-weight: 600;
}

/* dashboard mock */
.mock-dash {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 14px;
  align-items: center;
  padding: 14px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--panel-2);
}
.md-ring {
  --c: var(--accent);
  width: 76px;
  height: 76px;
}
.md-bars {
  display: grid;
  gap: 7px;
  font-size: 11.5px;
  color: var(--muted);
}
.md-bars span {
  display: grid;
  gap: 3px;
}
.md-bars i {
  order: 2;
  display: block;
  height: 5px;
  border-radius: 9px;
  background: var(--accent);
  box-shadow: inset 0 0 0 0 transparent;
}
.md-heat {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: repeat(14, 1fr);
  gap: 3px;
}
.md-heat i {
  aspect-ratio: 1;
  border-radius: 3px;
  background: var(--border);
}
.md-heat i[data-l="1"] {
  background: color-mix(in srgb, var(--ok) 35%, var(--border));
}
.md-heat i[data-l="2"] {
  background: color-mix(in srgb, var(--ok) 65%, var(--border));
}
.md-heat i[data-l="3"] {
  background: var(--ok);
}

/* coach mock */
.mock-chat {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.mock-chat p {
  font-size: 13px !important;
  line-height: 1.5;
  padding: 9px 12px;
  border-radius: 12px;
  max-width: 92%;
}
.mock-chat .me {
  align-self: flex-end;
  background: var(--accent);
  color: #fff !important;
  border-bottom-right-radius: 4px;
}
.mock-chat .bot {
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text) !important;
  border-bottom-left-radius: 4px;
}

/* ------------------------------------------------------------ curriculum */
.syllabus {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  align-items: start;
}
.part {
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--panel);
  padding: 18px 10px 10px;
}
.part:nth-child(4) {
  grid-row: span 2;
}
.part h3 {
  display: flex;
  flex-direction: column;
  font-size: 18px;
  margin: 0 10px 10px;
}
.part h3 span {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}
.part ol {
  list-style: none;
  padding: 0;
  margin: 0;
}
.part li a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 10px;
  border-radius: 10px;
  color: var(--text);
  text-decoration: none;
  font-size: 14.5px;
  font-weight: 500;
  line-height: 1.35;
}
.part li a:hover {
  background: var(--panel-2);
}
.part li .glyph {
  flex: none;
  color: var(--accent);
}
.part li a span {
  margin-left: auto;
  padding-left: 8px;
  font-size: 12.5px;
  color: var(--muted);
  white-space: nowrap;
}
.syllabus-cta {
  display: block;
  margin: 8px 10px 6px;
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
}

/* ------------------------------------------------------------ problems */
.problems {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}
.prob {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
  color: var(--text);
  text-decoration: none;
  transition: border-color 0.15s, transform 0.15s;
}
.prob:hover {
  border-color: var(--border-strong);
  transform: translateY(-2px);
}
.prob .glyph {
  flex: none;
  width: 34px;
  height: 34px;
  padding: 7px;
  border-radius: 9px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text);
}
.prob b {
  font-size: 14.5px;
  font-weight: 600;
  line-height: 1.3;
}
.lvl {
  margin-left: auto;
  font-size: 11.5px;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 99px;
  white-space: nowrap;
}
.lvl.easy {
  color: var(--lvl-basic);
  background: color-mix(in srgb, var(--lvl-basic) 14%, transparent);
}
.lvl.medium {
  color: var(--lvl-core);
  background: color-mix(in srgb, var(--lvl-core) 14%, transparent);
}
.lvl.hard {
  color: var(--lvl-pro);
  background: color-mix(in srgb, var(--lvl-pro) 14%, transparent);
}

/* ------------------------------------------------------------ pricing */
.plans {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 400px));
  justify-content: center;
  gap: 18px;
}
.plan {
  display: flex;
  flex-direction: column;
  padding: 28px;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: var(--panel);
}
.plan.featured {
  border-color: color-mix(in srgb, var(--accent) 55%, var(--border));
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent) 25%, transparent);
}
.plan-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}
.plan h3 {
  margin: 0;
  font-size: 18px;
}
.plan-badge {
  font-size: 12px;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 99px;
  background: var(--accent-soft);
  color: var(--accent);
}
.plan-badge.muted {
  background: var(--panel-2);
  color: var(--muted);
}
.plan-price {
  display: flex;
  align-items: baseline;
  gap: 8px;
  margin: 18px 0 18px;
}
.plan-price b {
  font-size: 44px;
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1;
}
.plan:not(.featured) .plan-price b {
  font-size: 30px;
}
.plan-price span {
  color: var(--muted);
  font-size: 15px;
}
.plan ul {
  list-style: none;
  padding: 0;
  margin: 0 0 24px;
  display: grid;
  gap: 10px;
  font-size: 14.5px;
}
.plan li {
  display: flex;
  gap: 9px;
  align-items: flex-start;
}
.plan li .glyph {
  flex: none;
  color: var(--ok);
  margin-top: 2px;
}
.plan-text {
  color: var(--muted);
  font-size: 14.5px;
  margin: 0 0 24px;
  flex: 1;
}
.plan .btn.block {
  justify-content: center;
  width: 100%;
  margin-top: auto;
}
.plan-note {
  text-align: center;
  font-size: 12.5px;
  color: var(--muted);
  margin: 10px 0 0;
}

/* ------------------------------------------------------------ faq */
.lp-faq-wrap {
  display: grid;
  grid-template-columns: minmax(0, 0.7fr) minmax(0, 1.3fr);
  gap: 48px;
  align-items: start;
}
/* intro and a contact card beside the questions (kept in view on wide screens) */
.faq-side {
  position: sticky;
  top: 96px;
}
.faq-side p {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 15.5px;
  line-height: 1.6;
}
.faq-help {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 12px 14px;
  align-items: center;
  margin-top: 26px;
  padding: 18px;
  border: 1px solid var(--glass-border, var(--border));
  border-radius: 16px;
  background: var(--glass-card, var(--panel));
  box-shadow: var(--glass-edge, none);
}
.faq-help > div {
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.faq-help > div span {
  color: var(--muted);
  font-size: 14px;
}
.faq-help .btn {
  grid-column: 1 / -1;
  justify-self: start;
}
.faq-help-ic {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 12px;
  background: color-mix(in srgb, var(--accent) 16%, transparent);
  color: var(--accent);
}

/* each question is its own glass card */
.faq {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.faq details {
  border: 1px solid var(--glass-border, var(--border));
  border-radius: 16px;
  background: var(--glass-card, var(--panel));
  box-shadow: var(--glass-edge, none);
  transition: border-color 0.2s, background 0.2s;
}
.faq details:hover {
  border-color: color-mix(in srgb, var(--accent) 30%, var(--glass-border, var(--border)));
}
.faq details[open] {
  border-color: color-mix(in srgb, var(--accent) 45%, transparent);
  background: linear-gradient(160deg, color-mix(in srgb, var(--accent) 9%, transparent), var(--glass-card, var(--panel)) 60%);
}
.faq summary {
  list-style: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 20px;
  font-size: 16.5px;
  font-weight: 600;
  border-radius: 16px;
}
.faq summary:focus-visible {
  outline: none;
  box-shadow: var(--focus);
}
.faq summary::-webkit-details-marker {
  display: none;
}
.faq summary::after {
  content: "+";
  display: grid;
  place-items: center;
  flex: none;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  border: 1px solid var(--glass-border-strong, var(--border-strong));
  font-size: 20px;
  font-weight: 400;
  line-height: 1;
  color: var(--muted);
  transition: transform 0.25s, background 0.2s, color 0.2s, border-color 0.2s;
}
.faq details[open] summary::after {
  transform: rotate(45deg);
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.faq details p {
  margin: 0;
  padding: 0 20px 20px;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.65;
  max-width: 720px;
}
.faq details[open] p {
  animation: faq-in 0.25s ease-out;
}
@keyframes faq-in {
  from {
    opacity: 0;
    transform: translateY(-4px);
  }
}
@media (prefers-reduced-motion: reduce) {
  .faq details[open] p {
    animation: none;
  }
}

/* ------------------------------------------------------------ final cta */
.lp-final {
  padding: 24px 0 96px;
}
.lp-final-inner {
  text-align: center;
  position: relative;
  padding-top: 72px;
  padding-bottom: 72px;
  border: 1px solid var(--border);
  border-radius: 24px;
  background: var(--panel);
  overflow: hidden;
  isolation: isolate;
}
.lp-final-inner::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background-image: linear-gradient(color-mix(in srgb, var(--text) 5%, transparent) 1px, transparent 1px),
    linear-gradient(90deg, color-mix(in srgb, var(--text) 5%, transparent) 1px, transparent 1px);
  background-size: 40px 40px;
  mask-image: radial-gradient(ellipse 70% 80% at 50% 50%, #000 20%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse 70% 80% at 50% 50%, #000 20%, transparent 75%);
}
.lp-final-inner > * {
  max-width: 760px;
  margin-left: auto;
  margin-right: auto;
}
.lp-final h2 {
  font-size: clamp(30px, 4vw, 48px);
  line-height: 1.1;
  letter-spacing: -0.035em;
  margin: 0 auto 14px;
  text-wrap: balance;
}
.lp-final p {
  color: var(--muted);
  font-size: 17px;
  margin: 0 auto 28px;
}

/* ------------------------------------------------------------ footer */
.lp-footer {
  border-top: 1px solid var(--border);
  background: var(--surface);
  padding: 48px 0 28px;
  font-size: 14px;
}
.lp-footer-grid {
  display: grid;
  grid-template-columns: 1.6fr repeat(3, 1fr);
  gap: 32px;
}
.lp-footer-brand p {
  color: var(--muted);
  max-width: 320px;
  margin: 12px 0 0;
}
.lp-footer nav {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.lp-footer h4 {
  margin: 0 0 4px;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}
.lp-footer nav a {
  color: var(--text);
  text-decoration: none;
}
.lp-footer nav a:hover {
  color: var(--accent);
}
.lp-footnote {
  margin-top: 36px;
}
.lp-footnote p {
  margin: 0;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 12.5px;
}
.lp-footer .lp-footnote a {
  color: var(--text);
}
.legal-foot {
  margin: 0;
}
.legal-foot p {
  border-top: 0;
  padding-top: 0;
}

/* ------------------------------------------------------------ legal pages */
.legal {
  max-width: 760px;
  margin: 0 auto;
  padding: 48px 24px 96px;
}
.legal h1 {
  font-size: clamp(32px, 4vw, 44px);
  letter-spacing: -0.035em;
  margin: 0 0 6px;
}
.legal .updated {
  color: var(--muted);
  margin: 0 0 32px;
}
.legal h2 {
  font-size: 20px;
  margin: 36px 0 10px;
}
.legal p,
.legal li {
  color: color-mix(in srgb, var(--text) 85%, var(--muted));
  font-size: 15.5px;
}
.legal .note {
  padding: 14px 16px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--panel);
  font-size: 14px;
}
.notfound {
  min-height: 70vh;
  display: grid;
  place-content: center;
  text-align: center;
  padding: 48px 24px;
}
.notfound .code {
  font-size: 15px;
  font-weight: 700;
  color: var(--accent);
}
.notfound h1 {
  font-size: clamp(32px, 5vw, 52px);
  letter-spacing: -0.04em;
  margin: 8px 0 10px;
}
.notfound p {
  color: var(--muted);
  margin: 0 0 26px;
}

/* ------------------------------------------------------------ responsive */
@media (max-width: 1080px) {
  .lp-hero-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .lp-hero-copy {
    max-width: 720px;
  }
  .lp-stats-row {
    grid-template-columns: repeat(3, 1fr);
  }
  .lp-stats-row > div:nth-child(3) {
    border-right: 0;
  }
  .lp-stats-row > div:nth-child(-n + 3) {
    border-bottom: 1px solid var(--border);
  }
  .lp-demo-body {
    grid-template-columns: 1fr;
  }
  .lp-demo-copy {
    border-right: 0;
    border-top: 1px solid var(--border);
  }
  .lp-demo-stage {
    order: -1;
  }
  .problems {
    grid-template-columns: repeat(3, 1fr);
  }
  .syllabus {
    grid-template-columns: repeat(2, 1fr);
  }
  .part:nth-child(4) {
    grid-row: auto;
  }
}
/* not enough room for every link: free lessons stay in the footer and the menu */
@media (max-width: 1120px) {
  .lp-link-more {
    display: none;
  }
}
@media (max-width: 860px) {
  .lp-links,
  .lp-login,
  .lp-pro {
    display: none !important;
  }
  .lp-menu {
    display: inline-grid !important;
  }
  .lp-steps {
    grid-template-columns: 1fr;
  }
  .bento {
    grid-template-columns: 1fr;
  }
  .tile.span-2 {
    grid-column: auto;
  }
  .plans {
    grid-template-columns: minmax(0, 480px);
  }
  .lp-faq-wrap {
    grid-template-columns: 1fr;
    gap: 24px;
  }
  .faq-side {
    position: static;
  }
  .lp-footer-grid {
    grid-template-columns: 1fr 1fr;
  }
  .lp-footer-brand {
    grid-column: 1 / -1;
  }
}
@media (max-width: 640px) {
  .lp-wrap {
    padding: 0 16px;
  }
  .lp-nav-inner {
    gap: 12px;
  }
  .lp-nav-cta .btn.primary {
    display: none;
  }
  .lp-brand span {
    font-size: 14.5px;
  }
  .lp-hero {
    padding: 32px 0 48px;
  }
  .lp-lead {
    font-size: 16.5px;
  }
  .lp-cta-row .btn {
    flex: 1 1 100%;
    justify-content: center;
  }
  .sim-metrics {
    grid-template-columns: repeat(2, 1fr);
  }
  .sim-metric:nth-child(2) {
    border-right: 0;
  }
  .sim-metric:nth-child(-n + 2) {
    border-bottom: 1px solid var(--border);
  }
  .sim-controls .btn {
    flex: 1 1 auto;
    justify-content: center;
  }
  .lp-stats-row {
    grid-template-columns: repeat(2, 1fr);
  }
  .lp-stats-row > div {
    border-bottom: 1px solid var(--border);
  }
  .lp-stats-row > div:nth-child(odd) {
    border-right: 1px solid var(--border);
  }
  .lp-stats-row > div:nth-child(even) {
    border-right: 0;
  }
  .lp-stats-row > div:nth-last-child(-n + 2) {
    border-bottom: 0;
  }
  .lp-section {
    padding: 64px 0;
  }
  .lp-head {
    margin-bottom: 32px;
  }
  .lp-demo-stage {
    padding: 12px;
    min-height: 0;
  }
  .problems,
  .syllabus {
    grid-template-columns: 1fr;
  }
  .mock-sim {
    grid-template-columns: 1fr;
  }
  .lp-footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}
@media (max-width: 380px) {
  .lp-nav-cta .btn.primary {
    padding: 6px 10px;
  }
  .lp-brand span {
    display: none;
  }
}
@media (prefers-reduced-motion: reduce) {
  .prob:hover {
    transform: none;
  }
  .sim-node.hot .sim-box {
    animation: none;
  }
}

/* ------------------------------------------------------------ certificate page */
.cert-wrap {
  max-width: 880px;
  margin: 0 auto;
  padding: 48px 20px 80px;
}
.cert {
  position: relative;
  padding: 56px 56px 44px;
  border-radius: 20px;
  border: 1px solid var(--border-strong);
  background: var(--panel);
  text-align: center;
  overflow: hidden;
}
.cert::before {
  content: "";
  position: absolute;
  inset: 12px;
  border: 1px solid color-mix(in srgb, var(--gold) 45%, transparent);
  border-radius: 12px;
  pointer-events: none;
}
.cert-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 17px;
}
.cert-brand b {
  color: var(--accent);
}
.cert-brand img {
  border-radius: 9px;
}
.cert-kicker {
  margin: 34px 0 6px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--gold);
}
.cert h1 {
  font-size: clamp(34px, 5vw, 52px);
  letter-spacing: -0.03em;
  margin: 0 0 16px;
}
.cert-text {
  max-width: 600px;
  margin: 0 auto 34px;
  color: var(--muted);
  font-size: 16px;
}
.cert-text b {
  color: var(--text);
}
.cert-meta {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  padding-top: 22px;
  border-top: 1px solid var(--border);
}
.cert-meta span {
  display: block;
  font-size: 12px;
  color: var(--muted);
}
.cert-meta b {
  font-size: 14px;
  word-break: break-all;
}
.cert-actions {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 22px;
}
.cert-verified {
  text-align: center;
  color: var(--ok);
  font-size: 14px;
}
@media (max-width: 640px) {
  .cert {
    padding: 40px 22px 30px;
  }
  .cert-meta {
    grid-template-columns: 1fr;
  }
}
@media print {
  .cert-page {
    background: #fff;
  }
  .cert-actions,
  .cert-verified {
    display: none;
  }
  .cert {
    border-color: #ccc;
    background: #fff;
    color: #111;
  }
}

/* ------------------------------------------------------------ free lesson pages (/learn) */
.learn-wrap {
  max-width: 1180px;
  margin: 0 auto;
  padding: 40px 24px 80px;
}
.learn-wrap.narrow {
  max-width: 780px;
}
.learn-head {
  margin: 0 0 28px;
}
.learn-head h1,
.learn-article h1 {
  font-size: clamp(32px, 4.2vw, 46px);
  line-height: 1.1;
  letter-spacing: -0.035em;
  margin: 6px 0 14px;
}
.learn-head > p {
  color: var(--muted);
  font-size: 17px;
  max-width: 680px;
  margin: 0;
}
.learn-crumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  font-size: 13.5px;
  color: var(--muted);
  margin-bottom: 22px;
}
.learn-crumbs a {
  color: var(--muted);
  text-decoration: none;
}
.learn-crumbs a:hover {
  color: var(--text);
}
.learn-crumbs .sep {
  opacity: 0.5;
}
.learn .prose {
  font-size: 16.5px;
  line-height: 1.7;
}
.learn .prose table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0;
}
.learn .prose th,
.learn .prose td {
  text-align: left;
  padding: 8px 10px;
  border-bottom: 1px solid var(--border);
}
.learn .keypoints {
  margin: 26px 0 0;
}
.learn-play {
  display: flex;
  align-items: center;
  gap: 14px;
  margin: 4px 0 26px;
  padding: 14px 18px;
  border-radius: 14px;
  border: 1px solid color-mix(in srgb, var(--accent) 45%, var(--border));
  background: var(--accent-soft);
  color: var(--text);
  text-decoration: none;
}
.learn-play:hover {
  border-color: var(--accent);
}
.learn-play .play-ico {
  display: inline-grid;
  place-items: center;
  flex: none;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  font-size: 14px;
}
.learn-play > span:last-child {
  display: flex;
  flex-direction: column;
}
.learn-play > span:last-child span {
  color: var(--muted);
  font-size: 14px;
}
.learn-pager {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 36px 0;
}
.learn-pager a {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--panel);
  color: var(--text);
  text-decoration: none;
}
.learn-pager a:hover {
  border-color: var(--border-strong);
}
.learn-pager a span {
  font-size: 12.5px;
  color: var(--muted);
}
.learn-pager .next {
  text-align: right;
  grid-column: 2;
}
.learn-cta {
  padding: 28px;
  border-radius: 18px;
  border: 1px solid var(--border);
  background: var(--panel);
  text-align: center;
}
.learn-cta h2 {
  margin: 0 0 8px;
  font-size: 24px;
}
.learn-cta p {
  color: var(--muted);
  margin: 0 auto 18px;
  max-width: 520px;
}
.learn-lessons {
  list-style: none;
  padding: 0;
  margin: 28px 0 0;
  display: grid;
  gap: 8px;
}
.learn-lessons a {
  display: flex;
  gap: 14px;
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--panel);
  color: var(--text);
  text-decoration: none;
}
.learn-lessons a:hover {
  border-color: var(--border-strong);
}
.learn-lessons .n {
  flex: none;
  font-weight: 700;
  color: var(--accent);
  min-width: 34px;
}
.learn-lessons a > span:last-child {
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.learn-lessons .muted {
  font-size: 14px;
}
.week-card {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin: 0 0 40px;
  padding: 24px 26px;
  border-radius: 18px;
  border: 1px solid color-mix(in srgb, var(--accent) 40%, var(--border));
  background: var(--accent-soft);
  color: var(--text);
  text-decoration: none;
  max-width: 780px;
}
.week-card b {
  font-size: 24px;
  letter-spacing: -0.02em;
}
.week-card > span:not(.lp-kicker) {
  color: var(--muted);
}
.week-card .week-more {
  color: var(--accent) !important;
  font-weight: 600;
}
.learn-part {
  margin: 0 0 40px;
}
.learn-part h2 {
  margin: 0 0 4px;
  font-size: 22px;
}
.learn-part > p {
  margin: 0 0 16px;
}
.learn-chapters {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 14px;
}
.learn-ch {
  padding: 18px 20px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
}
.learn-ch h3 {
  margin: 0 0 8px;
  font-size: 16px;
}
.learn-ch h3 a {
  color: var(--text);
  text-decoration: none;
}
.learn-ch ol {
  margin: 0;
  padding-left: 20px;
  font-size: 14px;
  line-height: 1.7;
}
.learn-ch li a {
  color: var(--muted);
  text-decoration: none;
}
.learn-ch li a:hover,
.learn-ch h3 a:hover {
  color: var(--accent);
}
@media (max-width: 640px) {
  .learn-wrap {
    padding: 28px 16px 64px;
  }
  .learn-pager {
    grid-template-columns: 1fr;
  }
  .learn-pager .next {
    grid-column: 1;
  }
}

/* stress test mock */
.mock-load {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background-color: var(--bg-2);
  background-image: radial-gradient(color-mix(in srgb, var(--muted) 18%, transparent) 1px, transparent 1px);
  background-size: 16px 16px;
}
.ml-row {
  display: flex;
  align-items: center;
  gap: 6px;
}
.ml-node {
  position: relative;
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 1px;
  padding: 9px 10px 13px;
  border: 1px solid var(--border-strong);
  border-radius: 10px;
  background: var(--panel);
  font-size: 12.5px;
}
.ml-node b {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.ml-node span {
  font-size: 11.5px;
  color: var(--muted);
}
.ml-node em {
  position: absolute;
  left: 10px;
  right: 10px;
  bottom: 6px;
  height: 3px;
  border-radius: 2px;
  background: color-mix(in srgb, var(--muted) 20%, transparent);
}
.ml-node em::after {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: var(--u);
  border-radius: inherit;
  background: var(--ok);
}
.ml-node small {
  position: absolute;
  top: 6px;
  right: 8px;
  font-size: 10.5px;
  font-weight: 700;
  color: var(--muted);
}
.ml-node.bad {
  border-color: var(--bad);
  background: color-mix(in srgb, var(--bad) 10%, var(--panel));
}
.ml-node.bad em::after {
  background: var(--bad);
}
.ml-node.bad small {
  color: var(--bad);
}
.ml-arrow {
  position: relative;
  flex: none;
  width: 14px;
  height: 2px;
  background: var(--border-strong);
}
.ml-arrow::after {
  content: "";
  position: absolute;
  top: -3px;
  right: -2px;
  border: 4px solid transparent;
  border-right: 0;
  border-left-color: var(--border-strong);
}
.ml-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.ml-chips span {
  padding: 4px 10px;
  border: 1px solid var(--border);
  border-radius: 99px;
  background: var(--panel);
  font-size: 12px;
  font-weight: 600;
}
.ml-chips .on {
  border-color: var(--accent);
  background: var(--accent);
  color: #fff;
}
.ml-verdict {
  margin: 0;
  font-size: 13.5px;
  color: var(--muted);
}
.ml-verdict b {
  color: var(--bad);
}
/* daily design mock */
.mock-share {
  margin: 0;
  padding: 16px 18px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--bg-2);
  font: 600 15px/1.75 Inter, system-ui, sans-serif;
  white-space: pre-wrap;
}
@media (max-width: 700px) {
  .ml-row {
    flex-wrap: wrap;
  }
  .ml-node {
    flex-basis: 40%;
  }
  .ml-arrow {
    display: none;
  }
}

/* contact page and locked lesson pages */
.contact-card {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 22px 0 8px;
  padding: 18px 20px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
}
.contact-card p {
  display: grid;
  grid-template-columns: 90px minmax(0, 1fr);
  gap: 10px;
  margin: 0;
}
.contact-card p[hidden] {
  display: none;
}
.learn-locked {
  margin: 22px 0;
  padding: 20px 22px;
  border: 1px solid var(--accent);
  border-radius: 14px;
  background: color-mix(in srgb, var(--accent) 8%, var(--panel));
}
.learn-locked b {
  font-size: 17px;
}
.learn-locked p {
  margin: 6px 0 14px;
  color: var(--muted);
}

/* ------------------------------------------------------------ 30-second tour */
.tour {
  display: grid;
  grid-template-columns: minmax(230px, 300px) minmax(0, 1fr);
  gap: 20px;
  align-items: stretch;
}
.tour-steps {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.tour-steps button {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 2px;
  width: 100%;
  padding: 12px 14px;
  overflow: hidden;
  border: 1px solid transparent;
  border-radius: 12px;
  background: none;
  color: var(--text);
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s;
}
.tour-steps button b {
  font-size: 15px;
}
.tour-steps button span {
  font-size: 13px;
  color: var(--muted);
}
.tour-steps button:hover {
  background: var(--panel);
}
.tour-steps button:focus-visible {
  outline: none;
  box-shadow: var(--focus);
}
.tour-steps button[aria-selected="true"] {
  border-color: var(--border);
  background: var(--panel);
}
.tour-bar {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
}
.tour-steps button[aria-selected="true"] .tour-bar {
  animation: tour-bar var(--tour-ms, 5500ms) linear forwards;
}
.tour.held .tour-bar {
  animation-play-state: paused;
}
@keyframes tour-bar {
  to {
    width: 100%;
  }
}
.tour-screen {
  position: relative;
  min-height: 340px;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 18px;
  background-color: var(--bg-2);
  background-image: radial-gradient(color-mix(in srgb, var(--muted) 16%, transparent) 1px, transparent 1px);
  background-size: 16px 16px;
}
.ts {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 24px;
  padding: 28px;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.4s;
}
.ts.on {
  opacity: 1;
  visibility: visible;
}
.ts-say {
  max-width: 520px;
  margin: 0;
  font-size: 14.5px;
  color: var(--muted);
  text-align: center;
}
.tw-node {
  --k: var(--k-server);
  display: inline-flex;
  align-items: center;
  padding: 10px 14px;
  border: 1.5px solid color-mix(in srgb, var(--k) 70%, var(--border));
  border-radius: 10px;
  background: color-mix(in srgb, var(--k) 12%, var(--panel));
  font-size: 13.5px;
  font-weight: 600;
  white-space: nowrap;
}
.c-client {
  --k: var(--k-client);
}
.c-lb {
  --k: var(--k-lb);
}
.c-server {
  --k: var(--k-server);
}
.c-cache {
  --k: var(--k-cache);
}
.c-db {
  --k: var(--k-db);
}
@keyframes tw-in {
  to {
    opacity: 1;
    transform: none;
  }
}
/* 1: requests flow; a server dies and traffic re-routes */
.tw-flow {
  display: flex;
  align-items: center;
}
.tw-wire {
  position: relative;
  width: 64px;
  height: 2px;
  background: var(--border-strong);
}
.tw-wire i {
  position: absolute;
  top: -3px;
  left: 0;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  opacity: 0;
}
.ts.on .tw-wire i {
  animation: tw-dot 1.6s linear infinite;
}
.ts.on .tw-wire i:nth-child(2) {
  animation-delay: 0.53s;
}
.ts.on .tw-wire i:nth-child(3) {
  animation-delay: 1.06s;
}
@keyframes tw-dot {
  0% {
    left: 0;
    opacity: 0;
  }
  12%,
  88% {
    opacity: 1;
  }
  100% {
    left: calc(100% - 8px);
    opacity: 0;
  }
}
.tw-stack {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.ts.on .tw-dead {
  animation: tw-dead 0.5s 1.4s forwards;
}
@keyframes tw-dead {
  to {
    border-color: var(--bad);
    background: color-mix(in srgb, var(--bad) 12%, var(--panel));
    color: var(--bad);
    text-decoration: line-through;
  }
}
/* 2: practice */
.tw-q {
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: min(440px, 100%);
}
.tw-q p {
  margin: 0 0 4px;
  font-weight: 600;
}
.tw-q span {
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--panel);
  font-size: 14px;
}
.ts.on .tw-right {
  animation: tw-right 0.4s 1.2s forwards;
}
@keyframes tw-right {
  to {
    border-color: var(--ok);
    background: color-mix(in srgb, var(--ok) 13%, var(--panel));
  }
}
/* 3: a design appears, then its score */
.tw-design {
  display: grid;
  grid-template-columns: repeat(3, auto);
  gap: 14px 18px;
  align-items: center;
  justify-items: center;
}
.tw-design .tw-node,
.tw-ring {
  opacity: 0;
  transform: translateY(6px);
}
.ts.on .tw-design .tw-node {
  animation: tw-in 0.4s forwards;
}
.ts.on .tw-design .tw-node:nth-child(2) {
  animation-delay: 0.3s;
}
.ts.on .tw-design .tw-node:nth-child(3) {
  animation-delay: 0.6s;
}
.ts.on .tw-design .tw-node:nth-child(4) {
  animation-delay: 0.9s;
}
.ts.on .tw-design .tw-node:nth-child(5) {
  animation-delay: 1.2s;
}
.tw-ring {
  display: grid;
  place-content: center;
  width: 78px;
  height: 78px;
  border-radius: 50%;
  background: radial-gradient(closest-side, var(--bg-2) 80%, transparent 82%), conic-gradient(var(--ok) 82%, var(--border) 0);
  text-align: center;
  line-height: 1;
}
.tw-ring b {
  font-size: 22px;
}
.tw-ring small {
  font-size: 11px;
  color: var(--muted);
}
.ts.on .tw-ring {
  animation: tw-in 0.4s 1.6s forwards;
}
/* 4: stress test */
.tw-meters {
  display: flex;
  flex-direction: column;
  gap: 12px;
  width: min(460px, 100%);
}
.tw-meters span {
  display: grid;
  grid-template-columns: 120px minmax(0, 1fr) 48px;
  align-items: center;
  gap: 10px;
  font-size: 13.5px;
}
.tw-meters i {
  position: relative;
  height: 8px;
  overflow: hidden;
  border-radius: 99px;
  background: var(--border);
}
.tw-meters i::after {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 0;
  border-radius: inherit;
  background: var(--ok);
}
.ts.on .tw-meters i::after {
  animation: tw-fill 1.4s 0.2s ease-out forwards;
}
@keyframes tw-fill {
  to {
    width: var(--u);
  }
}
.tw-meters .bad i::after {
  background: var(--bad);
}
.tw-meters em {
  font-style: normal;
  font-weight: 700;
  text-align: right;
}
.tw-meters .bad b,
.tw-meters .bad em {
  color: var(--bad);
}
/* 5: coach */
.tw-chat {
  display: flex;
  flex-direction: column;
  gap: 10px;
  width: min(460px, 100%);
}
.tw-chat p {
  margin: 0;
  padding: 10px 13px;
  opacity: 0;
  transform: translateY(6px);
  font-size: 14px;
  line-height: 1.5;
}
.tw-chat .me {
  align-self: flex-end;
  max-width: 82%;
  border-radius: 14px 14px 4px 14px;
  background: var(--accent);
  color: #fff;
}
.tw-chat .bot {
  align-self: flex-start;
  border: 1px solid var(--border);
  border-radius: 14px 14px 14px 4px;
  background: var(--panel);
}
.ts.on .tw-chat .me {
  animation: tw-in 0.35s 0.2s forwards;
}
.ts.on .tw-chat .bot {
  animation: tw-in 0.35s 1.2s forwards;
}
/* 6: daily puzzle */
.tw-daily {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 18px 22px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
  font-size: 15px;
}
.tw-tiles {
  display: flex;
  gap: 6px;
  font-size: 26px;
}
.tw-tiles i {
  font-style: normal;
  opacity: 0;
  transform: scale(0.6);
}
.ts.on .tw-tiles i {
  animation: tw-in 0.3s forwards;
}
.ts.on .tw-tiles i:nth-child(1) {
  animation-delay: 0.2s;
}
.ts.on .tw-tiles i:nth-child(2) {
  animation-delay: 0.5s;
}
.ts.on .tw-tiles i:nth-child(3) {
  animation-delay: 0.8s;
}
@media (max-width: 860px) {
  .tour {
    grid-template-columns: 1fr;
  }
  .tour-steps {
    flex-direction: row;
    overflow-x: auto;
    scrollbar-width: none;
  }
  .tour-steps button {
    min-width: 190px;
  }
}
@media (max-width: 560px) {
  .tour-screen {
    min-height: 360px;
  }
  .ts {
    padding: 18px 14px;
  }
  .tw-wire {
    width: 24px;
  }
  .tw-node {
    padding: 8px 9px;
    font-size: 12px;
  }
  .tw-meters span {
    grid-template-columns: 96px minmax(0, 1fr) 42px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .tw-design .tw-node,
  .tw-ring,
  .tw-chat p,
  .tw-tiles i {
    opacity: 1;
    transform: none;
    animation: none !important;
  }
  .tw-meters i::after {
    width: var(--u);
    animation: none !important;
  }
  .tw-wire i,
  .tour-bar {
    display: none;
  }
}

.plan-alt {
  margin: -6px 0 6px;
  font-size: 14px;
  color: var(--muted);
}
.plan-alt b {
  color: var(--text);
}

/* header "Go Pro" link: visible on wide screens; the mobile menu has its own */
.lp-pro {
  border-color: color-mix(in srgb, var(--warn) 55%, var(--border));
  color: var(--warn);
}
.lp-pro span {
  opacity: 0.75;
  font-weight: 500;
}
.lp-pro:hover {
  background: color-mix(in srgb, var(--warn) 12%, transparent);
  color: var(--warn);
}
@media (max-width: 1080px) {
  .lp-pro {
    display: none;
  }
}

/* ============================================================ growth features */
.lp-invite {
  display: flex;
  align-items: center;
  gap: 8px;
  width: fit-content;
  margin: 0 0 14px;
  padding: 8px 14px;
  border: 1px solid color-mix(in srgb, var(--ok) 40%, transparent);
  border-radius: 999px;
  background: color-mix(in srgb, var(--ok) 12%, transparent);
  font-size: 14px;
}
.lp-invite[hidden] {
  display: none;
}
.lp-invite i {
  display: inline-flex;
  color: var(--ok);
}
.lp-ready {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-top: 14px;
  color: var(--muted);
  font-size: 14.5px;
  text-decoration: none;
}
.lp-ready i {
  display: inline-flex;
  color: var(--accent);
}
.lp-ready b {
  color: var(--text);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: color-mix(in srgb, var(--accent) 60%, transparent);
}
.lp-ready:hover b {
  color: var(--accent);
}
.tile-new {
  margin-left: 6px;
  padding: 1px 7px;
  border-radius: 999px;
  background: var(--accent);
  color: #fff;
  font: 600 10.5px Inter, system-ui, sans-serif;
  font-style: normal;
  letter-spacing: 0.03em;
}
.mock-voice {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.mock-voice p {
  max-width: 88%;
  margin: 0;
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  font-size: 14px;
  line-height: 1.5;
}
.mock-voice b {
  display: block;
  font-size: 11px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--muted);
}
.mock-voice .mv-a {
  align-self: flex-end;
  background: color-mix(in srgb, var(--accent) 14%, var(--panel));
}
.mv-wave {
  display: flex;
  align-items: center;
  gap: 4px;
  height: 28px;
}
.mv-wave i {
  width: 4px;
  height: 40%;
  border-radius: 2px;
  background: var(--accent);
  animation: mv-wave 1.1s ease-in-out infinite;
}
.mv-wave i:nth-child(2) {
  animation-delay: 0.1s;
}
.mv-wave i:nth-child(3) {
  animation-delay: 0.2s;
}
.mv-wave i:nth-child(4) {
  animation-delay: 0.3s;
}
.mv-wave i:nth-child(5) {
  animation-delay: 0.4s;
}
.mv-wave i:nth-child(6) {
  animation-delay: 0.5s;
}
.mv-wave i:nth-child(7) {
  animation-delay: 0.6s;
}
.mv-wave span {
  margin-left: 8px;
  color: var(--muted);
  font-size: 13px;
}
@keyframes mv-wave {
  50% {
    height: 100%;
  }
}
@media (prefers-reduced-motion: reduce) {
  .mv-wave i {
    animation: none;
  }
}
.tile-ready {
  justify-content: space-between;
}
.tile-ready .btn {
  align-self: flex-start;
}
.mock-levels {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.mock-levels span {
  padding: 5px 10px;
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--muted);
  font-size: 13px;
}
.mock-levels span.on {
  border-color: var(--accent);
  background: color-mix(in srgb, var(--accent) 16%, transparent);
  color: var(--text);
  font-weight: 600;
}
.mock-levels p {
  flex-basis: 100%;
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 13.5px;
}
.mock-levels p b {
  color: var(--text);
}

/* ------------------------------------------------------------ the Playground intro */
.lp-pg {
  position: relative;
  overflow: hidden;
}
.lp-pg::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background: radial-gradient(55% 45% at 50% 60%, color-mix(in srgb, var(--accent) 13%, transparent), transparent 75%);
}
.lp-new {
  display: inline-block;
  margin-right: 10px;
  padding: 2px 9px;
  border-radius: 99px;
  background: var(--grad, var(--accent));
  color: #fff;
  font-size: 11px;
  letter-spacing: 0.08em;
  vertical-align: 1px;
}
.lp-pg-stage {
  position: relative;
  height: clamp(460px, 50vw, 620px);
  overflow: hidden;
  border: 1px solid var(--glass-border-strong, var(--border));
  border-radius: 28px;
  background:
    radial-gradient(70% 80% at 50% 50%, color-mix(in srgb, var(--accent) 9%, transparent), transparent 72%),
    linear-gradient(180deg, color-mix(in srgb, var(--panel) 75%, transparent), color-mix(in srgb, var(--bg) 88%, transparent));
  box-shadow: var(--glass-edge, none), 0 50px 120px -50px color-mix(in srgb, var(--accent) 45%, transparent);
}
/* the picture shown until the 3D scene is ready (and instead of it without WebGL) */
.lp-pg-still {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  padding: 7% 5%;
  transition: opacity 0.6s;
}
.lp-pg-stage.live .lp-pg-still {
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.6s, visibility 0s 0.6s;
}
.pgs-lines path {
  fill: none;
  stroke: color-mix(in srgb, var(--accent) 60%, var(--muted));
  stroke-width: 2;
  stroke-dasharray: 6 7;
}
.pgs-boxes rect {
  fill: color-mix(in srgb, var(--k, var(--muted)) 14%, var(--bg-2));
  stroke: var(--k, var(--muted));
  stroke-width: 1.5;
}
.pgs-boxes text,
.pgs-grade text {
  fill: var(--text);
  font: 600 15px Inter, system-ui, sans-serif;
  text-anchor: middle;
}
.pgs-grade rect {
  fill: var(--glass-solid, var(--panel));
  stroke: var(--glass-border-strong, var(--border));
}
.pgs-grade text {
  text-anchor: start;
  font-size: 16px;
  font-weight: 750;
}
.pgs-grade .pgs-a {
  fill: var(--ok);
  font-size: 34px;
  font-weight: 800;
  text-anchor: middle;
}
.pgs-grade .pgs-sub {
  fill: var(--muted);
  font-size: 12.5px;
  font-weight: 500;
}
.lp-pg-3d {
  position: absolute;
  inset: 0;
}
.lp-pg-foot {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 22px 36px;
  margin-top: 30px;
}
.lp-pg-points {
  display: flex;
  flex-wrap: wrap;
  gap: 16px 34px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.lp-pg-points li {
  display: flex;
  align-items: flex-start;
  gap: 11px;
  font-size: 14px;
  line-height: 1.45;
  color: var(--muted);
}
.lp-pg-points b {
  display: block;
  color: var(--text);
  font-weight: 650;
}
.lp-pg-points svg {
  flex: none;
  margin-top: 2px;
  color: var(--accent);
}
.lp-pg-cta {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--muted);
}

/* ---- the 3D scene and what floats over it (js/landing/playground3d.js) */
.ps3 > canvas {
  position: absolute;
  inset: 0;
  display: block;
  width: 100%;
  height: 100%;
  opacity: 0;
  transition: opacity 0.8s;
}
.ps3.on > canvas {
  opacity: 1;
}
.ps3-labels,
.ps3-ui {
  position: absolute;
  inset: 0;
  pointer-events: none;
}
.ps3-label {
  position: absolute;
  top: 0;
  left: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 4px 10px 5px;
  border: 1px solid var(--glass-border-strong, var(--border));
  border-radius: 9px;
  background: color-mix(in srgb, var(--bg) 72%, transparent);
  -webkit-backdrop-filter: blur(6px);
  backdrop-filter: blur(6px);
  color: var(--text);
  font: 650 12px/1.25 Inter, system-ui, sans-serif;
  white-space: nowrap;
  opacity: 0;
  will-change: transform;
}
.ps3-label span {
  color: var(--muted);
  font: 500 11px/1.3 Inter, system-ui, sans-serif;
  font-variant-numeric: tabular-nums;
}
.ps3-label span:empty {
  display: none;
}
.ps3-label[data-s="hot"] span {
  color: var(--warn);
  font-weight: 650;
}
.ps3-label[data-s="over"] {
  border-color: color-mix(in srgb, var(--bad) 60%, transparent);
}
.ps3-label[data-s="over"] span {
  color: var(--bad);
  font-weight: 700;
}
.ps3-hud {
  position: absolute;
  top: 18px;
  left: 18px;
  display: flex;
  align-items: center;
  gap: 10px;
  max-width: calc(100% - 36px);
  padding: 8px 15px 8px 13px;
  overflow: hidden;
  border: 1px solid var(--glass-border-strong, var(--border));
  border-radius: 999px;
  background: var(--glass-solid, var(--panel));
  box-shadow: var(--glass-edge, none), var(--shadow-lg);
  color: var(--text);
  font: 500 13px Inter, system-ui, sans-serif;
  white-space: nowrap;
  opacity: 0;
  transform: translateY(-8px);
  transition: opacity 0.4s, transform 0.4s, border-color 0.3s;
}
.ps3-hud.show {
  opacity: 1;
  transform: none;
}
.ps3-hud i {
  position: relative;
  flex: none;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  color: var(--muted);
  background: currentColor;
}
.ps3-hud i::after {
  content: "";
  position: absolute;
  inset: -4px;
  border: 2px solid currentColor;
  border-radius: 50%;
  opacity: 0;
  animation: ps3-ping 1.6s ease-out infinite;
}
@keyframes ps3-ping {
  0% {
    opacity: 0.8;
    transform: scale(0.6);
  }
  100% {
    opacity: 0;
    transform: scale(1.7);
  }
}
.ps3-hud[data-s="ok"] i {
  color: var(--ok);
}
.ps3-hud[data-s="warn"] i {
  color: var(--warn);
}
.ps3-hud[data-s="bad"] i {
  color: var(--bad);
}
.ps3-hud[data-s="bad"] {
  border-color: color-mix(in srgb, var(--bad) 55%, transparent);
}
.ps3-mult {
  min-width: 2.6ch;
  font-size: 16px;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}
.ps3-name {
  color: var(--muted);
}
.ps3-stats {
  display: flex;
  gap: 12px;
  padding-left: 12px;
  border-left: 1px solid var(--glass-border-strong, var(--border));
  color: var(--muted);
}
.ps3-stats b {
  color: var(--text);
  font-weight: 650;
  font-variant-numeric: tabular-nums;
}
.ps3-hud[data-s="bad"] .ps3-stats span:first-child b {
  color: var(--bad);
}
.ps3-burst {
  position: absolute;
  top: 17%;
  left: 50%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  opacity: 0;
  transform: translate(-50%, -50%) scale(0.8);
  transition: opacity 0.25s, transform 0.5s cubic-bezier(0.3, 1.6, 0.5, 1);
}
.ps3-burst.show {
  opacity: 1;
  transform: translate(-50%, -50%) scale(1);
}
.ps3-burst b {
  color: var(--bad);
  font: 800 clamp(34px, 5.2vw, 64px) / 1 Inter, system-ui, sans-serif;
  letter-spacing: -0.035em;
  white-space: nowrap;
  text-shadow: 0 0 44px color-mix(in srgb, var(--bad) 60%, transparent);
}
.ps3-burst span {
  padding: 5px 13px;
  border: 1px solid color-mix(in srgb, var(--bad) 45%, transparent);
  border-radius: 99px;
  background: color-mix(in srgb, var(--bad) 16%, var(--glass-solid, var(--panel)));
  color: var(--text);
  font: 600 13px Inter, system-ui, sans-serif;
  white-space: nowrap;
}
.ps3-card {
  position: absolute;
  display: flex;
  border: 1px solid var(--glass-border-strong, var(--border));
  border-radius: 16px;
  background: var(--glass-solid, var(--panel));
  box-shadow: var(--glass-edge, none), var(--shadow-lg);
  opacity: 0;
  transform: translateY(12px) scale(0.95);
  transition: opacity 0.35s, transform 0.55s cubic-bezier(0.3, 1.5, 0.5, 1);
}
.ps3-card.show {
  opacity: 1;
  transform: none;
}
.ps3-card-k {
  color: var(--accent);
  font: 700 11px Inter, system-ui, sans-serif;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}
.ps3-fix {
  top: 18px;
  right: 18px;
  flex-direction: column;
  gap: 7px;
  min-width: 220px;
  padding: 13px 16px;
}
.ps3-fix-row {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  font-size: 13.5px;
}
.ps3-fix-row em {
  color: var(--ok);
  font-style: normal;
  font-weight: 700;
}
.ps3-grade {
  top: 18px;
  right: 18px;
  align-items: center;
  gap: 16px;
  padding: 16px 24px 16px 16px;
}
.ps3-medal {
  display: grid;
  flex: none;
  place-items: center;
  width: 70px;
  height: 70px;
  border-radius: 20px;
  background: linear-gradient(135deg, #34d399, #16a34a);
  box-shadow: 0 0 40px rgba(34, 197, 94, 0.5), inset 0 1px 0 rgba(255, 255, 255, 0.35);
  color: #fff;
  font: 800 40px/1 Inter, system-ui, sans-serif;
}
.ps3-grade.show .ps3-medal {
  animation: ps3-stamp 0.6s 0.15s cubic-bezier(0.3, 1.6, 0.5, 1) both;
}
@keyframes ps3-stamp {
  from {
    opacity: 0;
    transform: scale(1.9) rotate(-8deg);
  }
}
.ps3-grade-text {
  display: flex;
  flex-direction: column;
  line-height: 1.3;
}
.ps3-grade-text b {
  font-size: 21px;
  font-weight: 800;
  letter-spacing: -0.02em;
}
.ps3-grade-text > span:not(.ps3-card-k):not(.ps3-flames) {
  color: var(--muted);
  font-size: 13px;
}
.ps3-flames {
  display: flex;
  gap: 3px;
  margin-top: 6px;
}
.ps3-flames i {
  width: 15px;
  height: 17px;
  background: color-mix(in srgb, var(--text) 16%, transparent);
  -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M12 21c3.9 0 6.5-2.6 6.5-6.2 0-3.5-2.4-5.6-3.6-8.3-.3 2-1.5 3.2-2.7 3.6.3-2.9-.9-5.7-3.4-7.1.2 3.1-1.8 5.1-3.3 7A7.4 7.4 0 0 0 5.5 15c0 3.5 2.7 6 6.5 6z'/%3E%3C/svg%3E") center / contain no-repeat;
  mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M12 21c3.9 0 6.5-2.6 6.5-6.2 0-3.5-2.4-5.6-3.6-8.3-.3 2-1.5 3.2-2.7 3.6.3-2.9-.9-5.7-3.4-7.1.2 3.1-1.8 5.1-3.3 7A7.4 7.4 0 0 0 5.5 15c0 3.5 2.7 6 6.5 6z'/%3E%3C/svg%3E") center / contain no-repeat;
  transition: background 0.3s, transform 0.3s;
}
.ps3-flames i.on {
  background: #ff7a3d;
  transform: scale(1.15);
}
.ps3-steps {
  position: absolute;
  bottom: 16px;
  left: 50%;
  display: flex;
  gap: 4px;
  padding: 5px;
  border: 1px solid var(--glass-border-strong, var(--border));
  border-radius: 99px;
  background: var(--glass-solid, var(--panel));
  box-shadow: var(--glass-edge, none), var(--shadow-lg);
  transform: translateX(-50%);
  pointer-events: auto;
}
.ps3-step {
  position: relative;
  overflow: hidden;
  padding: 7px 14px;
  border: 0;
  border-radius: 99px;
  background: transparent;
  color: var(--muted);
  font: 600 12.5px Inter, system-ui, sans-serif;
  white-space: nowrap;
  cursor: pointer;
  transition: color 0.2s, background 0.2s;
}
.ps3-step i {
  position: absolute;
  bottom: 0;
  left: 14px;
  right: 14px;
  height: 2px;
  border-radius: 2px;
  background: var(--accent);
  transform: scaleX(var(--p, 0));
  transform-origin: left;
}
.ps3-step:hover,
.ps3-step.done {
  color: var(--text);
}
.ps3-step.on {
  background: color-mix(in srgb, var(--accent) 16%, transparent);
  color: var(--text);
}
.ps3-step:focus-visible {
  outline: none;
  box-shadow: var(--focus);
}
.ps3.still .ps3-steps {
  display: none;
}
@media (max-width: 900px) {
  .lp-pg-foot {
    flex-direction: column;
    align-items: stretch;
  }
  .lp-pg-cta {
    align-items: stretch;
    text-align: center;
  }
}
@media (max-width: 640px) {
  .lp-pg-stage {
    height: 600px;
    border-radius: 22px;
  }
  .ps3-label {
    padding: 3px 7px 4px;
    font-size: 10.5px;
  }
  .ps3-label span {
    font-size: 10px;
  }
  .ps3-hud {
    top: 12px;
    left: 12px;
    gap: 8px;
    font-size: 12px;
  }
  .ps3-name {
    display: none;
  }
  .ps3-fix {
    top: 62px;
    right: 12px;
    min-width: 0;
  }
  .ps3-grade {
    top: 56px;
    right: 12px;
    left: 12px;
    justify-content: center;
    padding: 10px 14px;
  }
  .ps3-burst {
    top: 22%;
  }
  .ps3-medal {
    width: 56px;
    height: 56px;
    font-size: 32px;
  }
  .ps3-steps {
    bottom: 12px;
    gap: 0;
  }
  .ps3-step {
    padding: 6px 8px;
    font-size: 11px;
  }
  .ps3-step i {
    left: 8px;
    right: 8px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ps3-hud i::after {
    animation: none;
  }
}

/* ------------------------------------------------------------ Reveal the answer + Fix it for me tiles */
.mock-reveal {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
  gap: 14px;
  align-items: center;
  flex: 1;
}
.mr-steps {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 13px;
  color: var(--muted);
}
.mr-steps li {
  display: flex;
  align-items: flex-start;
  gap: 9px;
  padding: 6px 8px;
  border: 1px solid transparent;
  border-radius: 10px;
}
.mr-steps i {
  display: grid;
  flex: none;
  place-items: center;
  width: 20px;
  height: 20px;
  border: 1.5px solid var(--border-strong);
  border-radius: 50%;
  font: 700 10.5px/1 Inter, system-ui, sans-serif;
  font-style: normal;
}
.mr-steps .done {
  color: var(--text);
}
.mr-steps .done i {
  border-color: var(--ok);
  background: var(--ok);
  color: #fff;
}
.mr-steps .on {
  border-color: color-mix(in srgb, var(--accent) 35%, transparent);
  background: color-mix(in srgb, var(--accent) 10%, transparent);
  color: var(--text);
}
.mr-steps .on i {
  border-color: var(--accent);
  background: var(--accent);
  color: #fff;
}
.mr-steps .on span {
  display: flex;
  flex-direction: column;
  gap: 2px;
  font-size: 12px;
  color: var(--muted);
}
.mr-steps .on b {
  color: var(--text);
  font-size: 13px;
}
.mr-canvas {
  width: 100%;
  height: auto;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: radial-gradient(color-mix(in srgb, var(--muted) 18%, transparent) 1px, transparent 1px) 0 0 / 14px 14px, var(--bg-2);
}
.mr-n rect {
  fill: color-mix(in srgb, var(--k, var(--muted)) 16%, var(--bg-2));
  stroke: var(--k, var(--muted));
  stroke-width: 1.4;
}
.mr-n text {
  fill: var(--text);
  font: 600 11px Inter, system-ui, sans-serif;
  text-anchor: middle;
}
.mr-l {
  fill: none;
  stroke: color-mix(in srgb, var(--accent) 65%, var(--muted));
  stroke-width: 1.6;
  stroke-dasharray: 60;
}
/* the design draws itself, one piece after another, then starts over */
.mr-n {
  animation: mr-in 8s infinite both;
}
.mr-l {
  animation: mr-draw 8s infinite both;
}
.mr-n2,
.mr-l1 {
  animation-delay: 0.5s;
}
.mr-n3,
.mr-l2 {
  animation-delay: 1s;
}
.mr-n4,
.mr-l3 {
  animation-delay: 1.6s;
}
.mr-n5,
.mr-l4 {
  animation-delay: 2.2s;
}
@keyframes mr-in {
  0% {
    opacity: 0;
  }
  6%,
  88% {
    opacity: 1;
  }
  96%,
  100% {
    opacity: 0;
  }
}
@keyframes mr-draw {
  0% {
    stroke-dashoffset: 60;
  }
  8%,
  88% {
    stroke-dashoffset: 0;
    opacity: 1;
  }
  96%,
  100% {
    stroke-dashoffset: 0;
    opacity: 0;
  }
}
.mock-fixit {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: auto;
  padding: 14px;
  border: 1px solid var(--border);
  border-left: 3px solid var(--warn);
  border-radius: 12px;
  background: var(--bg-2);
}
.mock-fixit .mf-text {
  color: var(--text);
  font-size: 13.5px;
}
.mf-btns {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.mf-btns span {
  padding: 5px 11px;
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  font-size: 12.5px;
  font-weight: 600;
}
.mf-btns .mf-primary {
  border-color: var(--btn-primary-edge, transparent);
  background: var(--btn-primary, var(--accent));
  color: var(--btn-primary-ink, #fff);
}
.mock-fixit .mf-result {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: 13px;
}
.mf-result b {
  color: var(--ok);
}
.mf-result em {
  padding: 1px 7px;
  border-radius: 99px;
  background: var(--ok);
  color: #fff;
  font-style: normal;
  font-weight: 700;
}
@media (max-width: 640px) {
  .mock-reveal {
    grid-template-columns: minmax(0, 1fr);
  }
}
@media (prefers-reduced-motion: reduce) {
  .mr-n,
  .mr-l {
    animation: none;
  }
  .mr-l {
    stroke-dashoffset: 0;
  }
}

/* ------------------------------------------------------------ interview question pages (/problems) */
.pd .learn-article h2 {
  margin: 40px 0 12px;
  font-size: 23px;
  letter-spacing: -0.02em;
}
.pd .learn-article > p,
.pd .learn-article > ul {
  color: color-mix(in srgb, var(--text) 86%, var(--muted));
  font-size: 16px;
  line-height: 1.7;
}
.pd-prompt {
  font-size: 18px !important;
  line-height: 1.6;
}
.pd-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 4px 0 22px;
}
.pd-tags span {
  padding: 3px 11px;
  border-radius: 99px;
  background: color-mix(in srgb, var(--text) 7%, transparent);
  color: var(--muted);
  font-size: 13px;
}
.pd-qa {
  display: grid;
  grid-template-columns: minmax(150px, 0.4fr) 1fr;
  margin: 0;
  border: 1px solid var(--border);
  border-radius: 14px;
  overflow: hidden;
}
.pd-qa dt,
.pd-qa dd {
  margin: 0;
  padding: 11px 14px;
  border-top: 1px solid var(--border);
  font-size: 15px;
  line-height: 1.55;
}
.pd-qa dt:first-of-type,
.pd-qa dt:first-of-type + dd {
  border-top: 0;
}
.pd-qa dt {
  font-weight: 650;
  background: color-mix(in srgb, var(--text) 4%, transparent);
}
.pd-est,
.pd-steps,
.pd-points {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 12px 0 0;
  padding: 0;
  list-style: none;
}
.pd-est li,
.pd-points li {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 11px 14px;
  border-left: 3px solid var(--ok);
  border-radius: 10px;
  background: color-mix(in srgb, var(--ok) 7%, transparent);
  font-size: 15px;
}
.pd-points li {
  border-left-color: var(--accent);
  background: color-mix(in srgb, var(--accent) 7%, transparent);
}
.pd-est span,
.pd-points span,
.pd-steps span {
  color: var(--muted);
  line-height: 1.6;
}
.pd-steps {
  counter-reset: step;
}
.pd-steps li {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 2px 0 2px 44px;
  font-size: 15.5px;
  counter-increment: step;
}
.pd-steps li::before {
  content: counter(step);
  position: absolute;
  top: 0;
  left: 0;
  display: grid;
  place-items: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: color-mix(in srgb, var(--accent) 16%, transparent);
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
}
.pd-fig {
  margin: 8px 0 22px;
  padding: 14px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: radial-gradient(color-mix(in srgb, var(--muted) 16%, transparent) 1px, transparent 1px) 0 0 / 16px 16px, var(--bg-2);
}
.pd-fig figcaption {
  margin-top: 8px;
  color: var(--muted);
  font-size: 13px;
  text-align: center;
}
.pd-svg {
  display: block;
  width: 100%;
  height: auto;
}
.pd-lines line {
  stroke: color-mix(in srgb, var(--accent) 55%, var(--muted));
  stroke-width: 1.8;
}
.pd-lines line.async {
  stroke-dasharray: 6 6;
}
.pd-svg marker path {
  fill: color-mix(in srgb, var(--accent) 55%, var(--muted));
}
.pd-boxes rect {
  fill: color-mix(in srgb, var(--k, var(--muted)) 14%, var(--bg-2));
  stroke: var(--k, var(--muted));
  stroke-width: 1.6;
}
.pd-label {
  fill: var(--text);
  font: 600 14px Inter, system-ui, sans-serif;
  text-anchor: middle;
}
.pd-tech {
  fill: var(--muted);
  font: 500 11.5px Inter, system-ui, sans-serif;
  text-anchor: middle;
}
.pd-parts {
  margin: 0;
}
.pd-parts dt {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px;
  margin-top: 14px;
  font-weight: 650;
  font-size: 15.5px;
}
.pd-parts dt > span {
  width: 10px;
  height: 10px;
  border-radius: 3px;
  background: var(--k, var(--muted));
}
.pd-parts dt small {
  color: var(--muted);
  font-weight: 500;
  font-size: 13px;
}
.pd-parts dd {
  margin: 3px 0 0 18px;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.6;
}
.pd-follow {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding-left: 22px;
  font-size: 15.5px;
  line-height: 1.6;
}
.pd-follow ul {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 14.5px;
}
.pd-lessons {
  font-size: 14.5px !important;
}
.pd-more {
  margin: 34px 0 10px;
}
.pd-more h2 {
  font-size: 19px;
}
.pd-more div {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.pd-more a {
  padding: 6px 12px;
  border: 1px solid var(--border);
  border-radius: 99px;
  color: var(--text);
  font-size: 14px;
  text-decoration: none;
}
.pd-more a:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.pd-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 280px), 1fr));
  gap: 12px;
}
.pd-card {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
  color: var(--text);
  text-decoration: none;
  transition: border-color 0.15s, transform 0.15s;
}
.pd-card:hover {
  border-color: color-mix(in srgb, var(--accent) 45%, var(--border));
  transform: translateY(-2px);
}
.pd-card b {
  font-size: 16px;
}
.pd-card span {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.5;
}
.pd-card small {
  margin-top: auto;
  color: var(--accent);
  font-size: 12.5px;
}
.probs-all {
  margin: 18px 0 0;
  text-align: center;
  font-weight: 600;
}
@media (max-width: 640px) {
  .pd-qa {
    grid-template-columns: minmax(0, 1fr);
  }
  .pd-qa dd {
    border-top: 0;
    padding-top: 0;
  }
  .pd-fig {
    overflow-x: auto;
  }
  .pd-svg {
    min-width: 560px;
  }
}