:root {
  --paper: #f5f1e8;
  --paper-strong: #fffdf7;
  --ink: #12202a;
  --muted: #607078;
  --line: #cfd5d0;
  --actor: #087f8c;
  --actor-soft: #d7f1ef;
  --critic: #d05d3b;
  --critic-soft: #f8dfd4;
  --target: #6f728f;
  --target-soft: #e8e7ef;
  --data: #147d64;
  --gradient: #e05236;
  --param: #5961a8;
  --acid: #d8e44e;
  --shadow: 0 18px 50px rgba(29, 43, 46, 0.09);
  --radius-lg: 28px;
  --radius-md: 18px;
  --font-display: "Avenir Next", "DIN Alternate", "PingFang SC", sans-serif;
  --font-body: "Avenir Next", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "SFMono-Regular", "Cascadia Code", "Menlo", monospace;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: var(--font-body);
  background:
    linear-gradient(rgba(22, 42, 44, 0.045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(22, 42, 44, 0.045) 1px, transparent 1px),
    radial-gradient(circle at 90% 4%, rgba(216, 228, 78, 0.24), transparent 24rem),
    var(--paper);
  background-size: 28px 28px, 28px 28px, auto, auto;
  min-height: 100vh;
  padding-bottom: 110px;
}

button,
input,
select {
  font: inherit;
}

button {
  color: inherit;
}

button:focus-visible,
input:focus-visible,
select:focus-visible,
[tabindex]:focus-visible {
  outline: 3px solid rgba(8, 127, 140, 0.32);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 100;
  transform: translateY(-150%);
  padding: 10px 14px;
  color: white;
  background: var(--ink);
  border-radius: 8px;
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  min-height: 76px;
  padding: 10px clamp(18px, 3vw, 48px);
  background: rgba(245, 241, 232, 0.88);
  border-bottom: 1px solid rgba(88, 98, 97, 0.18);
  backdrop-filter: blur(18px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  width: max-content;
  color: inherit;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 50% 50% 45% 55%;
  color: white;
  background: var(--ink);
  font: 700 24px/1 Georgia, serif;
  transform: rotate(-7deg);
}

.brand strong,
.brand small {
  display: block;
}

.brand strong {
  font-size: 14px;
  letter-spacing: 0.08em;
}

.brand small {
  margin-top: 3px;
  color: var(--muted);
  font: 10px/1 var(--font-mono);
  letter-spacing: 0.1em;
}

.header-center {
  display: flex;
  gap: 4px;
  padding: 4px;
  background: rgba(255, 253, 247, 0.72);
  border: 1px solid var(--line);
  border-radius: 999px;
}

.algorithm-tab {
  display: flex;
  align-items: center;
  gap: 8px;
  min-height: 40px;
  padding: 0 18px;
  border: 0;
  border-radius: 999px;
  background: transparent;
  cursor: pointer;
  font-weight: 700;
}

.algorithm-tab span {
  color: var(--muted);
  font: 10px var(--font-mono);
}

.algorithm-tab i {
  display: grid;
  place-items: center;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  color: var(--muted);
  background: #e4e4dd;
  font-size: 9px;
  font-style: normal;
}

.algorithm-tab.is-active {
  color: white;
  background: var(--ink);
  box-shadow: 0 8px 18px rgba(18, 32, 42, 0.18);
}

.algorithm-tab.is-active span {
  color: var(--acid);
}

.algorithm-tab.is-unlocked i {
  color: #153a31;
  background: var(--acid);
}

.mastery {
  justify-self: end;
  display: grid;
  grid-template-columns: auto auto;
  gap: 5px 12px;
  align-items: center;
  min-width: 154px;
}

.mastery-label {
  color: var(--muted);
  font-size: 11px;
}

.mastery strong {
  justify-self: end;
  font: 700 12px var(--font-mono);
}

.mastery-track {
  grid-column: 1 / -1;
  height: 4px;
  overflow: hidden;
  background: #d9d9d1;
  border-radius: 99px;
}

.mastery-track i {
  display: block;
  width: 16.667%;
  height: 100%;
  background: var(--actor);
  border-radius: inherit;
  transition: width 400ms ease;
}

main {
  width: min(1560px, calc(100% - 32px));
  margin: 0 auto;
}

.algorithm-view {
  animation: reveal 420ms ease both;
}

.algorithm-view[hidden] {
  display: none;
}

.intro-strip {
  display: grid;
  grid-template-columns: minmax(420px, 1fr) minmax(280px, 0.72fr) auto;
  gap: 44px;
  align-items: end;
  padding: 64px 12px 38px;
}

.eyebrow,
.stage-kicker,
.panel-label {
  margin: 0 0 12px;
  color: var(--actor);
  font: 700 10px/1.3 var(--font-mono);
  letter-spacing: 0.16em;
}

h1,
h2,
h3,
p {
  text-wrap: pretty;
}

.intro-strip h1,
.sac-hero h1 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(38px, 4.4vw, 70px);
  line-height: 0.99;
  letter-spacing: -0.055em;
}

.intro-strip h1 em,
.sac-hero h1 em {
  color: var(--critic);
  font-family: Georgia, "Songti SC", serif;
  font-weight: 400;
}

.intro-copy {
  margin: 0;
  color: #4d6067;
  font-size: 15px;
  line-height: 1.8;
}

.mode-switch {
  display: flex;
  gap: 4px;
  padding: 4px;
  background: var(--paper-strong);
  border: 1px solid var(--line);
  border-radius: 12px;
  box-shadow: var(--shadow);
}

.mode-switch button {
  min-width: 72px;
  padding: 10px 16px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  cursor: pointer;
  font-size: 13px;
  font-weight: 700;
}

.mode-switch button.is-active {
  color: white;
  background: var(--ink);
}

.workbench {
  display: grid;
  grid-template-columns: 206px minmax(540px, 1fr) 286px;
  min-height: 720px;
  overflow: hidden;
  background: var(--paper-strong);
  border: 1px solid #bbc5c1;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
}

.lesson-rail,
.explain-panel {
  padding: 26px 20px;
  background: rgba(243, 241, 233, 0.82);
}

.lesson-rail {
  border-right: 1px solid var(--line);
}

.rail-heading {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 18px;
  color: var(--muted);
  font: 700 10px var(--font-mono);
  letter-spacing: 0.08em;
}

.step-list {
  display: grid;
  gap: 7px;
}

.step-button {
  position: relative;
  display: grid;
  grid-template-columns: 27px 1fr;
  gap: 9px;
  align-items: center;
  width: 100%;
  min-height: 56px;
  padding: 8px 8px;
  text-align: left;
  border: 1px solid transparent;
  border-radius: 13px;
  background: transparent;
  cursor: pointer;
  transition: background 180ms ease, border-color 180ms ease, transform 180ms ease;
}

.step-button:hover {
  background: rgba(255, 255, 255, 0.75);
  transform: translateX(2px);
}

.step-button.is-active {
  background: white;
  border-color: #c2ccc8;
  box-shadow: 0 8px 20px rgba(24, 42, 44, 0.07);
}

.step-button.is-complete::after {
  content: "✓";
  position: absolute;
  right: 8px;
  top: 8px;
  color: var(--data);
  font-size: 10px;
}

.step-number {
  display: grid;
  place-items: center;
  width: 27px;
  height: 27px;
  border: 1px solid #b7c0bc;
  border-radius: 50%;
  color: var(--muted);
  font: 10px var(--font-mono);
}

.step-button.is-active .step-number {
  color: white;
  background: var(--actor);
  border-color: var(--actor);
}

.step-label strong,
.step-label small {
  display: block;
}

.step-label strong {
  font-size: 12px;
  line-height: 1.35;
}

.step-label small {
  margin-top: 3px;
  color: var(--muted);
  font: 9px var(--font-mono);
}

.rail-note {
  display: flex;
  gap: 9px;
  align-items: flex-start;
  margin-top: 28px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
}

.pulse-dot {
  flex: 0 0 auto;
  width: 8px;
  height: 8px;
  margin-top: 5px;
  border-radius: 50%;
  background: var(--acid);
  box-shadow: 0 0 0 5px rgba(216, 228, 78, 0.24);
}

.rail-note p {
  margin: 0;
  color: var(--muted);
  font-size: 10px;
  line-height: 1.55;
}

.rail-note strong {
  display: block;
  color: var(--ink);
}

.learning-stage {
  min-width: 0;
  padding: 28px clamp(22px, 3vw, 42px) 34px;
  background:
    radial-gradient(circle at 50% 28%, rgba(8, 127, 140, 0.07), transparent 20rem),
    var(--paper-strong);
}

.stage-heading {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  align-items: flex-end;
}

.stage-heading h2 {
  margin: 0;
  font-size: clamp(23px, 2vw, 32px);
  letter-spacing: -0.035em;
}

.step-meter {
  flex: 0 0 90px;
  text-align: right;
}

.step-meter span {
  font: 700 11px var(--font-mono);
}

.step-meter div {
  height: 3px;
  margin-top: 7px;
  overflow: hidden;
  background: #dbddd8;
  border-radius: 99px;
}

.step-meter i {
  display: block;
  height: 100%;
  background: var(--actor);
  transition: width 300ms ease;
}

.flow-legend {
  display: flex;
  gap: 5px;
  margin: 24px 0 16px;
  padding-bottom: 14px;
  overflow-x: auto;
  border-bottom: 1px solid #e1e3de;
}

.flow-legend button {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 7px 9px;
  white-space: nowrap;
  border: 1px solid transparent;
  border-radius: 8px;
  background: transparent;
  cursor: pointer;
  font-size: 10px;
  font-weight: 700;
  opacity: 0.48;
  transition: opacity 180ms ease, background 180ms ease;
}

.flow-legend button span {
  color: var(--muted);
  font-weight: 400;
}

.flow-legend button.is-active,
.flow-legend button:hover {
  opacity: 1;
  background: #f2f3ed;
  border-color: #d9ddd8;
}

.line-sample {
  width: 22px;
  height: 3px;
  border-radius: 5px;
}

.line-data {
  background: var(--data);
}

.line-gradient {
  background: repeating-linear-gradient(90deg, var(--gradient) 0 4px, transparent 4px 7px);
}

.line-param {
  height: 2px;
  border-top: 2px dotted var(--param);
}

.flow-canvas {
  position: relative;
  min-height: 488px;
  padding: 16px;
  border: 1px solid #d8ddd8;
  border-radius: 22px;
  background:
    linear-gradient(rgba(58, 79, 78, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(58, 79, 78, 0.035) 1px, transparent 1px),
    #fbfbf6;
  background-size: 18px 18px;
  overflow: hidden;
}

.data-band {
  display: grid;
  grid-template-columns: 95px minmax(140px, 1fr) 110px;
  gap: 14px;
  align-items: center;
  max-width: 560px;
  margin: 0 auto 18px;
  padding: 10px;
  border: 1px solid #c8d7d1;
  border-radius: 14px;
  background: rgba(236, 246, 241, 0.75);
  opacity: 0.42;
  transition: opacity 250ms ease, box-shadow 250ms ease;
}

body[data-flow="data"] .data-band {
  opacity: 1;
  box-shadow: 0 8px 24px rgba(20, 125, 100, 0.1);
}

.band-label {
  position: absolute;
  transform: translate(-5px, -34px);
  color: var(--data);
  font: 700 8px var(--font-mono);
  letter-spacing: 0.14em;
}

.mini-node {
  display: flex;
  gap: 7px;
  align-items: center;
  font-size: 10px;
  font-weight: 700;
}

.mini-node i {
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 9px;
  color: white;
  background: var(--data);
  font: 8px var(--font-mono);
}

.mini-node.replay i {
  color: var(--ink);
  background: var(--acid);
}

.moving-arrow {
  position: relative;
  text-align: center;
  color: var(--data);
  font: 9px var(--font-mono);
  overflow: hidden;
}

.moving-arrow::after {
  content: "";
  position: absolute;
  left: -30%;
  bottom: -2px;
  width: 30%;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--data));
  animation: move-line 1.8s linear infinite;
}

.network-headings {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 112px;
  max-width: 610px;
  margin: 0 auto 7px;
  color: var(--muted);
  font: 700 9px var(--font-mono);
  text-transform: uppercase;
}

.network-headings span:last-child {
  text-align: right;
}

.network-headings small {
  margin-left: 4px;
  color: #9a9f9d;
  font-weight: 400;
}

.network-board {
  display: grid;
  grid-template-columns: minmax(160px, 1fr) 82px minmax(160px, 1fr);
  gap: 12px;
  max-width: 610px;
  margin: auto;
}

.network-card {
  position: relative;
  min-height: 132px;
  padding: 13px;
  border: 1px solid #cfd6d2;
  border-radius: 17px;
  background: rgba(255, 255, 255, 0.86);
  box-shadow: 0 8px 24px rgba(27, 49, 48, 0.06);
  opacity: 0.46;
  transition: opacity 220ms ease, transform 220ms ease, box-shadow 220ms ease, border-color 220ms ease;
}

.network-card.is-active {
  opacity: 1;
  transform: translateY(-2px);
  box-shadow: 0 14px 30px rgba(27, 49, 48, 0.12);
}

.network-card.is-source {
  border-color: var(--param);
  box-shadow: 0 0 0 3px rgba(89, 97, 168, 0.12), 0 14px 30px rgba(27, 49, 48, 0.1);
}

.network-card.receives-gradient {
  border-color: var(--gradient);
  box-shadow: 0 0 0 3px rgba(224, 82, 54, 0.13), 0 14px 30px rgba(27, 49, 48, 0.1);
}

.network-card.is-focused {
  opacity: 1;
  transform: translateY(-4px) scale(1.025);
  box-shadow: 0 0 0 4px rgba(216, 228, 78, 0.6), 0 18px 36px rgba(27, 49, 48, 0.14);
}

.network-card.actor {
  border-top: 4px solid var(--actor);
}

.network-card.critic {
  border-top: 4px solid var(--critic);
}

.network-card.target {
  background: linear-gradient(135deg, rgba(247, 246, 251, 0.95), rgba(235, 234, 242, 0.85));
}

.network-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.network-index {
  color: var(--muted);
  font: 700 9px var(--font-mono);
}

.status-pill {
  padding: 3px 6px;
  color: var(--actor);
  background: var(--actor-soft);
  border-radius: 99px;
  font: 700 7px var(--font-mono);
  letter-spacing: 0.08em;
}

.critic .status-pill {
  color: #8e3c25;
  background: var(--critic-soft);
}

.target .status-pill {
  color: var(--target);
  background: var(--target-soft);
}

.network-card p {
  margin: 10px 0 1px;
  font-size: 11px;
  font-weight: 700;
}

.network-card h3 {
  margin: 0 0 5px;
  font: 700 22px var(--font-display);
  letter-spacing: -0.04em;
}

.network-card h3 sub {
  font-size: 11px;
}

.network-card > small {
  color: var(--muted);
  font-size: 9px;
}

.update-badge,
.copy-badge {
  position: absolute;
  right: 10px;
  bottom: 9px;
  padding: 4px 6px;
  border-radius: 6px;
  font: 700 7px var(--font-mono);
  opacity: 0;
  transform: translateY(3px);
  transition: opacity 180ms ease, transform 180ms ease;
}

.update-badge {
  color: #9b361f;
  background: #ffe4d8;
}

.copy-badge {
  color: #4f568e;
  background: #e9e8f7;
}

.receives-gradient .update-badge,
body[data-flow="param"] .network-card.target.is-active .copy-badge {
  opacity: 1;
  transform: translateY(0);
}

.soft-arrow {
  display: grid;
  place-items: center;
  align-content: center;
  color: var(--param);
  opacity: 0.28;
  transition: opacity 200ms ease;
}

.soft-arrow span,
.soft-arrow small {
  font: 7px var(--font-mono);
}

.soft-arrow i {
  font-style: normal;
  letter-spacing: -0.18em;
  transform-origin: left;
}

body[data-flow="param"] .soft-arrow {
  opacity: 1;
}

body[data-flow="param"] .soft-arrow i {
  animation: soft-pulse 1.6s ease-in-out infinite;
}

.gradient-band {
  display: flex;
  justify-content: center;
  gap: 11px;
  align-items: center;
  max-width: 520px;
  margin: 16px auto 0;
  padding: 9px 12px;
  color: #9b3f29;
  border: 1px dashed rgba(224, 82, 54, 0.45);
  border-radius: 10px;
  background: rgba(255, 237, 231, 0.75);
  font-size: 9px;
  opacity: 0.28;
  transition: opacity 200ms ease;
}

.gradient-band strong {
  font: 700 10px var(--font-mono);
}

.gradient-band i {
  font-style: normal;
}

body[data-flow="gradient"] .gradient-band {
  opacity: 1;
  animation: gradient-glow 1.4s ease-in-out infinite alternate;
}

.canvas-caption {
  margin: 13px 0 0;
  text-align: center;
  color: var(--muted);
  font-size: 10px;
}

.stage-story {
  display: grid;
  grid-template-columns: 48px 1fr;
  gap: 14px;
  margin-top: 18px;
  padding-top: 17px;
  border-top: 1px solid #e0e2dd;
}

.story-number {
  color: #c7ccc7;
  font: 700 34px/1 var(--font-display);
}

.stage-story p {
  margin: 0;
  font-size: 13px;
  line-height: 1.65;
}

.route-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 11px;
}

.route-pills span {
  padding: 5px 8px;
  border-radius: 7px;
  background: #edf0eb;
  font: 700 8px var(--font-mono);
}

.route-pills .actor-route {
  color: #056872;
  background: var(--actor-soft);
}

.route-pills .critic-route {
  color: #9b3f29;
  background: var(--critic-soft);
}

.route-pills .target-route {
  color: #4f568e;
  background: var(--target-soft);
}

.explain-panel {
  border-left: 1px solid var(--line);
}

.explain-tabs {
  display: flex;
  gap: 18px;
  margin-bottom: 28px;
  border-bottom: 1px solid var(--line);
}

.explain-tabs button {
  position: relative;
  padding: 0 0 11px;
  border: 0;
  background: transparent;
  cursor: pointer;
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.explain-tabs button.is-active {
  color: var(--ink);
}

.explain-tabs button.is-active::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: -1px;
  left: 0;
  height: 3px;
  background: var(--acid);
}

.explain-content {
  display: none;
  animation: reveal 240ms ease both;
}

.explain-content.is-active {
  display: block;
}

.explain-content h3 {
  margin: 0 0 12px;
  font-size: 23px;
  line-height: 1.18;
  letter-spacing: -0.035em;
}

.explain-content > p:not(.panel-label, .tap-tip) {
  color: var(--muted);
  font-size: 12px;
  line-height: 1.75;
}

.change-box,
.freeze-box {
  margin-top: 22px;
  padding: 14px;
  border-radius: 13px;
}

.change-box {
  color: #733320;
  background: var(--critic-soft);
  border: 1px solid #e9c4b5;
}

.freeze-box {
  background: #ebece7;
  border: 1px solid #d7d9d3;
}

.change-box span,
.freeze-box span {
  display: block;
  margin-bottom: 5px;
  font: 700 8px var(--font-mono);
  letter-spacing: 0.08em;
}

.change-box strong {
  font-size: 12px;
}

.freeze-box p {
  margin: 0;
  color: var(--muted);
  font-size: 10px;
  line-height: 1.6;
}

.math-formula {
  padding: 14px;
  overflow-x: auto;
  color: #263846;
  background: white;
  border: 1px solid var(--line);
  border-radius: 13px;
  font: 600 11px/1.8 var(--font-mono);
}

.math-formula button {
  padding: 2px 4px;
  border: 0;
  border-radius: 4px;
  color: #076b75;
  background: var(--actor-soft);
  cursor: pointer;
}

.tap-tip {
  color: #7a8589;
  font-size: 9px;
}

.quick-check {
  margin-top: 34px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
}

.quick-check > p {
  color: var(--muted);
  font: 700 8px var(--font-mono);
  letter-spacing: 0.12em;
}

.quick-check button {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  width: 100%;
  padding: 11px 0;
  text-align: left;
  border: 0;
  background: transparent;
  cursor: pointer;
  font-size: 11px;
  line-height: 1.5;
  font-weight: 700;
}

.quick-check button i {
  font-size: 18px;
  font-style: normal;
  transition: transform 180ms ease;
}

.quick-check button.is-open i {
  transform: rotate(45deg);
}

#check-answer {
  padding: 11px;
  color: #45565c;
  background: #eef2ed;
  border-radius: 9px;
  font-size: 10px;
  line-height: 1.6;
}

.lab-section {
  padding: 92px 4px 32px;
}

.section-heading {
  display: flex;
  justify-content: space-between;
  gap: 36px;
  align-items: end;
  margin-bottom: 28px;
}

.section-heading h2,
.compare-teaser h2,
.entropy-lab h2 {
  margin: 0;
  font-size: clamp(30px, 3vw, 48px);
  line-height: 1.03;
  letter-spacing: -0.05em;
}

.section-heading > p {
  max-width: 380px;
  margin: 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.7;
}

.lab-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}

.lab-card {
  position: relative;
  min-width: 0;
  padding: 24px;
  overflow: hidden;
  background: var(--paper-strong);
  border: 1px solid #bdc8c4;
  border-radius: 22px;
  box-shadow: 0 12px 36px rgba(35, 49, 50, 0.07);
}

.lab-card::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  height: 5px;
  background: var(--critic);
}

.actor-lab::before {
  background: var(--actor);
}

.soft-lab::before {
  background: var(--param);
}

.lab-card-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--muted);
  font: 700 8px var(--font-mono);
  letter-spacing: 0.08em;
}

.lab-card-head strong {
  padding: 5px 7px;
  color: var(--ink);
  background: #ebece5;
  border-radius: 6px;
}

.lab-card h3 {
  margin: 20px 0 14px;
  font-size: 21px;
  letter-spacing: -0.035em;
}

.formula-display {
  min-height: 64px;
  padding: 12px;
  overflow-x: auto;
  color: #33474d;
  background: #f0f1eb;
  border-radius: 10px;
  font: 600 10px/1.8 var(--font-mono);
}

.formula-display button {
  padding: 2px 3px;
  border: 0;
  border-bottom: 1px solid currentColor;
  color: var(--actor);
  background: transparent;
  cursor: pointer;
}

.formula-display button:hover {
  background: var(--actor-soft);
}

.control-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 18px;
}

.lab-card label {
  display: block;
  color: #55666d;
  font-size: 9px;
  font-weight: 700;
}

.lab-card label output {
  float: right;
  color: var(--ink);
  font: 700 9px var(--font-mono);
}

input[type="range"] {
  width: 100%;
  height: 4px;
  margin-top: 11px;
  appearance: none;
  border-radius: 99px;
  background: #d7dbd6;
  accent-color: var(--actor);
}

input[type="range"]::-webkit-slider-thumb {
  width: 15px;
  height: 15px;
  appearance: none;
  border: 3px solid var(--paper-strong);
  border-radius: 50%;
  background: var(--actor);
  box-shadow: 0 0 0 1px #98aaa8;
  cursor: grab;
}

input[type="range"]:active::-webkit-slider-thumb {
  cursor: grabbing;
}

.critic-lab input[type="range"]::-webkit-slider-thumb {
  background: var(--critic);
}

.soft-lab input[type="range"]::-webkit-slider-thumb {
  background: var(--param);
}

.terminal-toggle {
  display: flex !important;
  gap: 8px;
  align-items: center;
  margin-top: 17px;
  cursor: pointer;
}

.terminal-toggle input {
  accent-color: var(--critic);
}

.critic-result {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 6px;
  margin-top: 17px;
}

.critic-result div {
  padding: 10px;
  background: #f0f1eb;
  border-radius: 9px;
}

.critic-result div.accent {
  color: #71311f;
  background: var(--critic-soft);
}

.critic-result span,
.critic-result strong {
  display: block;
}

.critic-result span {
  color: var(--muted);
  font-size: 8px;
}

.critic-result strong {
  margin-top: 5px;
  font: 700 16px var(--font-mono);
}

.lab-insight {
  margin: 16px 0 0;
  padding-top: 14px;
  color: var(--muted);
  border-top: 1px solid #e1e2dc;
  font-size: 10px;
  line-height: 1.65;
}

.q-landscape {
  position: relative;
  height: 130px;
  margin: 18px 0;
  overflow: hidden;
  border-bottom: 1px solid #adb8b5;
  background:
    linear-gradient(rgba(43, 67, 67, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(43, 67, 67, 0.06) 1px, transparent 1px);
  background-size: 20px 20px;
}

.hill {
  position: absolute;
  right: 7%;
  bottom: -58%;
  width: 72%;
  height: 142%;
  border: 3px solid var(--actor);
  border-bottom: 0;
  border-radius: 50% 50% 0 0;
  transform: rotate(-4deg);
  opacity: 0.68;
}

.actor-marker {
  position: absolute;
  left: 35%;
  bottom: 0;
  height: 77%;
  border-left: 2px dashed var(--critic);
  transition: left 180ms ease, height 180ms ease;
}

.actor-marker i {
  position: absolute;
  top: -5px;
  left: -6px;
  width: 11px;
  height: 11px;
  border: 3px solid white;
  border-radius: 50%;
  background: var(--critic);
  box-shadow: 0 0 0 1px var(--critic);
}

.actor-marker span {
  position: absolute;
  top: 9px;
  left: 7px;
  width: max-content;
  color: #923d27;
  font-size: 8px;
  font-weight: 700;
}

.axis-min,
.axis-max,
.peak-label {
  position: absolute;
  color: var(--muted);
  font: 8px var(--font-mono);
}

.axis-min {
  bottom: 4px;
  left: 4px;
}

.axis-max {
  right: 4px;
  bottom: 4px;
}

.peak-label {
  top: 8px;
  right: 10px;
  color: var(--actor);
}

.actor-result {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 7px;
  margin-top: 16px;
}

.actor-result div {
  padding: 10px;
  background: var(--actor-soft);
  border-radius: 9px;
}

.actor-result span,
.actor-result strong {
  display: block;
}

.actor-result span {
  color: #41696c;
  font-size: 8px;
}

.actor-result strong {
  margin-top: 5px;
  font: 700 15px var(--font-mono);
}

.actor-result p {
  grid-column: 1 / -1;
  margin: 2px 0 0;
  color: var(--actor);
  font-size: 9px;
  line-height: 1.5;
}

.parameter-track {
  position: relative;
  height: 78px;
  margin: 27px 8px 9px;
  border-top: 4px solid #d6d9d5;
}

.parameter-track > span {
  position: absolute;
  top: 8px;
  color: var(--muted);
  font: 8px var(--font-mono);
}

.parameter-track > span:nth-child(1) {
  left: 0;
}

.parameter-track > span:nth-child(2) {
  left: 50%;
}

.parameter-track > span:nth-child(3) {
  right: 0;
}

.param-dot {
  position: absolute;
  top: -8px;
  left: 50%;
  width: 13px;
  height: 13px;
  border: 3px solid white;
  border-radius: 50%;
  box-shadow: 0 0 0 1px #88938f;
  transition: left 240ms ease;
}

.param-dot b {
  position: absolute;
  top: 17px;
  left: 50%;
  width: max-content;
  color: var(--muted);
  font: 7px var(--font-mono);
  transform: translateX(-50%);
}

.param-dot.old {
  background: #aaaebc;
}

.param-dot.online {
  background: var(--actor);
}

.param-dot.new {
  top: -22px;
  background: var(--acid);
  box-shadow: 0 0 0 1px #8e9731;
}

.param-dot.new b {
  top: -16px;
  color: #68711c;
}

.soft-result {
  padding: 13px;
  color: #444b82;
  background: var(--target-soft);
  border-radius: 11px;
}

.soft-result span {
  font-size: 9px;
}

.soft-result strong {
  float: right;
  font: 700 17px var(--font-mono);
}

.soft-result p {
  margin: 7px 0 0;
  font-size: 9px;
}

.compare-teaser {
  display: grid;
  grid-template-columns: 1fr 1fr auto;
  gap: 50px;
  align-items: center;
  margin: 60px 0 28px;
  padding: clamp(30px, 4vw, 58px);
  color: white;
  background:
    radial-gradient(circle at 85% 20%, rgba(216, 228, 78, 0.22), transparent 18rem),
    var(--ink);
  border-radius: 28px;
  overflow: hidden;
}

.compare-teaser .eyebrow {
  color: var(--acid);
}

.teaser-map {
  display: grid;
  grid-template-columns: 1fr auto 1.2fr;
  gap: 12px;
  align-items: center;
  font-size: 11px;
}

.teaser-map span {
  color: #aebfc3;
}

.teaser-map i {
  color: var(--acid);
  font-style: normal;
}

.cta-button {
  display: inline-flex;
  justify-content: space-between;
  gap: 24px;
  align-items: center;
  min-width: 190px;
  padding: 15px 18px;
  color: var(--ink);
  background: var(--acid);
  border: 0;
  border-radius: 12px;
  cursor: pointer;
  font-size: 11px;
  font-weight: 800;
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.16);
  transition: transform 180ms ease;
}

.cta-button:hover {
  transform: translateY(-2px);
}

.control-dock {
  position: fixed;
  z-index: 40;
  right: 50%;
  bottom: 18px;
  display: flex;
  gap: 5px;
  align-items: center;
  padding: 6px;
  color: white;
  background: rgba(18, 32, 42, 0.94);
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 16px;
  box-shadow: 0 14px 40px rgba(10, 22, 29, 0.25);
  backdrop-filter: blur(16px);
  transform: translateX(50%);
}

.control-dock > button {
  min-height: 42px;
  padding: 0 13px;
  color: #d7e1e2;
  border: 0;
  border-radius: 10px;
  background: transparent;
  cursor: pointer;
  font-size: 11px;
  font-weight: 700;
}

.control-dock > button:hover {
  color: white;
  background: rgba(255, 255, 255, 0.08);
}

.control-dock > button:disabled {
  opacity: 0.34;
  cursor: not-allowed;
}

.control-dock .play-button {
  min-width: 114px;
  color: var(--ink);
  background: var(--acid);
}

.control-dock .play-button:hover {
  color: var(--ink);
  background: #e9f267;
}

.play-button i {
  margin-right: 6px;
  font-size: 9px;
  font-style: normal;
}

.speed-control {
  display: flex;
  gap: 5px;
  align-items: center;
  margin-left: 3px;
  padding-left: 9px;
  border-left: 1px solid rgba(255, 255, 255, 0.16);
  color: #aebcc0;
  font-size: 9px;
}

.speed-control select {
  padding: 7px 22px 7px 8px;
  color: white;
  border: 0;
  border-radius: 7px;
  background: #2a3a43;
}

.toast {
  position: fixed;
  z-index: 60;
  top: 92px;
  right: 22px;
  max-width: 310px;
  padding: 12px 15px;
  color: white;
  background: var(--ink);
  border-left: 4px solid var(--acid);
  border-radius: 9px;
  box-shadow: var(--shadow);
  font-size: 11px;
  line-height: 1.5;
  opacity: 0;
  pointer-events: none;
  transform: translateY(-8px);
  transition: opacity 180ms ease, transform 180ms ease;
}

.toast.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.sac-view {
  padding: 72px 0 30px;
}

.sac-hero {
  max-width: 900px;
  margin: 0 auto;
  text-align: center;
}

.sac-hero .eyebrow {
  margin-top: 42px;
}

.sac-hero > p:last-child {
  max-width: 570px;
  margin: 28px auto;
  color: var(--muted);
  line-height: 1.8;
}

.text-button {
  padding: 9px 13px;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: var(--paper-strong);
  cursor: pointer;
  font-size: 11px;
  font-weight: 700;
}

.sac-gate {
  max-width: 560px;
  margin: 60px auto;
  padding: 48px;
  text-align: center;
  background: var(--paper-strong);
  border: 1px solid var(--line);
  border-radius: 24px;
  box-shadow: var(--shadow);
}

.sac-gate > span {
  display: grid;
  place-items: center;
  width: 55px;
  height: 55px;
  margin: auto;
  color: var(--ink);
  background: var(--acid);
  border-radius: 50%;
  font: 700 16px var(--font-mono);
}

.sac-gate h2 {
  margin: 20px 0 7px;
}

.sac-gate p {
  margin: 0 0 23px;
  color: var(--muted);
  font-size: 12px;
}

.sac-gate .cta-button {
  margin: auto;
}

.sac-content {
  max-width: 1180px;
  margin: 70px auto 0;
}

.comparison-table {
  overflow: hidden;
  background: var(--paper-strong);
  border: 1px solid #bcc6c2;
  border-radius: 20px;
  box-shadow: var(--shadow);
}

.compare-row {
  display: grid;
  grid-template-columns: 0.65fr 1fr 1fr;
}

.compare-row > * {
  padding: 19px 22px;
  border-bottom: 1px solid #dce0dc;
}

.compare-row > * + * {
  border-left: 1px solid #dce0dc;
}

.compare-row:last-child > * {
  border-bottom: 0;
}

.compare-row span {
  color: var(--muted);
  font-size: 11px;
}

.compare-row strong {
  font-size: 12px;
}

.compare-row.head {
  color: white;
  background: var(--ink);
}

.compare-row.head span {
  color: #cbd7d9;
}

.compare-row.head strong:last-child {
  color: var(--acid);
}

.entropy-lab {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 70px;
  align-items: center;
  margin-top: 24px;
  padding: 54px;
  background: var(--paper-strong);
  border: 1px solid #bcc6c2;
  border-radius: 24px;
}

.entropy-lab > div:first-child > p:last-child {
  color: var(--muted);
  font-size: 12px;
  line-height: 1.7;
}

.entropy-control label {
  display: block;
  color: var(--muted);
  font-size: 11px;
  font-weight: 700;
}

.entropy-control output {
  float: right;
  color: var(--ink);
  font: 700 12px var(--font-mono);
}

.distribution {
  display: flex;
  gap: 7px;
  align-items: end;
  height: 170px;
  margin: 26px 0 15px;
  padding: 12px;
  border-bottom: 1px solid var(--line);
  background:
    linear-gradient(rgba(43, 67, 67, 0.06) 1px, transparent 1px);
  background-size: 100% 25px;
}

.distribution i {
  flex: 1;
  min-height: 8px;
  border-radius: 7px 7px 0 0;
  background: var(--actor);
  transition: height 220ms ease;
}

.entropy-control > strong {
  color: var(--actor);
  font-size: 12px;
}

body[data-mode="infer"] .soft-arrow,
body[data-mode="infer"] .gradient-band,
body[data-mode="infer"] .network-card.critic,
body[data-mode="infer"] .network-card.target {
  opacity: 0.12 !important;
  animation: none !important;
}

body[data-mode="infer"] .network-card.online.actor {
  opacity: 1;
  border-color: var(--actor);
  box-shadow: 0 0 0 3px rgba(8, 127, 140, 0.1);
}

@keyframes reveal {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes move-line {
  to {
    left: 110%;
  }
}

@keyframes soft-pulse {
  0%,
  100% {
    transform: scaleX(0.75);
    opacity: 0.5;
  }
  50% {
    transform: scaleX(1);
    opacity: 1;
  }
}

@keyframes gradient-glow {
  from {
    box-shadow: 0 0 0 rgba(224, 82, 54, 0);
  }
  to {
    box-shadow: 0 0 20px rgba(224, 82, 54, 0.12);
  }
}

@media (max-width: 1180px) {
  .workbench {
    grid-template-columns: 180px 1fr;
  }

  .explain-panel {
    grid-column: 1 / -1;
    display: grid;
    grid-template-columns: 160px 1fr 1fr;
    gap: 22px;
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  .explain-tabs {
    display: block;
    border: 0;
  }

  .explain-tabs button {
    display: block;
    width: 100%;
    margin-bottom: 6px;
    padding: 9px;
    border-radius: 8px;
    text-align: left;
  }

  .explain-tabs button.is-active {
    color: white;
    background: var(--ink);
  }

  .explain-tabs button.is-active::after {
    display: none;
  }

  .explain-content {
    grid-column: 2;
  }

  .quick-check {
    grid-column: 3;
    margin-top: 0;
    padding: 0;
    border: 0;
  }

  .lab-grid {
    grid-template-columns: 1fr 1fr;
  }

  .soft-lab {
    grid-column: 1 / -1;
  }

  .compare-teaser {
    grid-template-columns: 1fr 1fr;
  }

  .compare-teaser .cta-button {
    grid-column: 1 / -1;
    width: max-content;
  }
}

@media (max-width: 800px) {
  body {
    padding-bottom: 84px;
  }

  .site-header {
    grid-template-columns: 1fr auto;
    min-height: 66px;
    padding: 9px 14px;
  }

  .brand small,
  .mastery-label {
    display: none;
  }

  .header-center {
    grid-row: 2;
    grid-column: 1 / -1;
    justify-content: center;
    margin-top: 8px;
  }

  .site-header {
    padding-bottom: 8px;
  }

  .mastery {
    min-width: 90px;
  }

  main {
    width: min(100% - 20px, 720px);
  }

  .intro-strip {
    grid-template-columns: 1fr;
    gap: 22px;
    padding: 44px 4px 25px;
  }

  .intro-strip h1 {
    font-size: clamp(38px, 11vw, 60px);
  }

  .mode-switch {
    width: 100%;
  }

  .mode-switch button {
    flex: 1;
  }

  .workbench {
    display: block;
    overflow: visible;
    border-radius: 22px;
  }

  .lesson-rail {
    position: sticky;
    top: 112px;
    z-index: 15;
    padding: 12px;
    overflow-x: auto;
    border-right: 0;
    border-bottom: 1px solid var(--line);
    border-radius: 22px 22px 0 0;
  }

  .rail-heading,
  .rail-note {
    display: none;
  }

  .step-list {
    display: flex;
    width: max-content;
  }

  .step-button {
    grid-template-columns: 24px 1fr;
    min-width: 140px;
    min-height: 48px;
  }

  .learning-stage {
    padding: 24px 14px 28px;
  }

  .stage-heading {
    align-items: start;
  }

  .stage-heading h2 {
    font-size: 22px;
  }

  .flow-canvas {
    min-height: 610px;
    padding: 12px 8px;
  }

  .data-band {
    grid-template-columns: 80px 1fr 88px;
    gap: 6px;
  }

  .network-headings {
    gap: 10px;
  }

  .network-board {
    grid-template-columns: 1fr 1fr;
    gap: 9px;
  }

  .soft-arrow {
    position: absolute;
    pointer-events: none;
  }

  .actor-arrow {
    top: 223px;
    left: calc(50% - 27px);
  }

  .critic-arrow {
    top: 368px;
    left: calc(50% - 27px);
  }

  .soft-arrow span,
  .soft-arrow small {
    display: none;
  }

  .soft-arrow i {
    font-size: 10px;
  }

  .network-card:nth-of-type(1) {
    grid-column: 1;
    grid-row: 1;
  }

  .network-card:nth-of-type(2) {
    grid-column: 2;
    grid-row: 1;
  }

  .network-card:nth-of-type(3) {
    grid-column: 1;
    grid-row: 2;
  }

  .network-card:nth-of-type(4) {
    grid-column: 2;
    grid-row: 2;
  }

  .network-card {
    min-height: 137px;
  }

  .gradient-band {
    flex-wrap: wrap;
  }

  .explain-panel {
    display: block;
    padding: 22px 16px;
  }

  .explain-tabs {
    display: flex;
  }

  .explain-tabs button {
    width: auto;
  }

  .explain-content,
  .quick-check {
    margin-top: 18px;
  }

  .lab-section {
    padding-top: 70px;
  }

  .section-heading {
    display: block;
  }

  .section-heading > p {
    margin-top: 15px;
  }

  .lab-grid {
    grid-template-columns: 1fr;
  }

  .soft-lab {
    grid-column: auto;
  }

  .compare-teaser {
    grid-template-columns: 1fr;
    gap: 28px;
    padding: 32px 24px;
  }

  .compare-teaser .cta-button {
    grid-column: auto;
    width: 100%;
  }

  .control-dock {
    right: 8px;
    bottom: 8px;
    left: 8px;
    justify-content: space-between;
    border-radius: 14px;
    transform: none;
  }

  .control-dock > button {
    min-width: 42px;
    padding: 0 9px;
  }

  .control-dock > button span,
  .speed-control span {
    display: none;
  }

  .control-dock .play-button {
    min-width: 48px;
  }

  .play-button i {
    margin: 0;
  }

  .sac-view {
    padding-top: 52px;
  }

  .sac-hero h1 {
    font-size: 40px;
  }

  .compare-row {
    grid-template-columns: 0.65fr 1fr 1fr;
  }

  .compare-row > * {
    padding: 13px 10px;
  }

  .entropy-lab {
    grid-template-columns: 1fr;
    gap: 30px;
    padding: 28px 20px;
  }
}

@media (max-width: 480px) {
  .algorithm-tab {
    padding: 0 14px;
  }

  .mastery {
    min-width: 74px;
  }

  .stage-heading {
    display: block;
  }

  .step-meter {
    width: 100%;
    margin-top: 14px;
    text-align: left;
  }

  .flow-legend button span {
    display: none;
  }

  .data-band {
    grid-template-columns: 1fr 1fr;
  }

  .moving-arrow {
    grid-column: 1 / -1;
    grid-row: 2;
  }

  .network-card {
    padding: 10px;
  }

  .network-card h3 {
    font-size: 18px;
  }

  .network-card > small {
    font-size: 8px;
  }

  .stage-story {
    grid-template-columns: 36px 1fr;
  }

  .story-number {
    font-size: 27px;
  }

  .control-grid,
  .critic-result {
    grid-template-columns: 1fr;
  }

  .comparison-table {
    overflow-x: auto;
  }

  .compare-row {
    min-width: 520px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}