:root {
  --ink: #112c3a;
  --muted: #5e7480;
  --paper: #f3f7f7;
  --white: #ffffff;
  --line: #d8e3e5;
  --navy: #0c2836;
  --navy-2: #103644;
  --cyan: #00c8d0;
  --cyan-deep: #00a8b1;
  --orange: #ff7449;
  --orange-deep: #e65e37;
  --shadow: 0 24px 70px rgba(20, 57, 69, 0.11);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 2% 8%, rgba(0, 200, 208, 0.07), transparent 23rem),
    var(--paper);
  font-family: Inter, "SF Pro Display", "PingFang SC", "Microsoft YaHei", sans-serif;
  -webkit-font-smoothing: antialiased;
}
button, input { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; text-decoration: none; }

.site-header {
  width: min(1280px, calc(100% - 48px));
  height: 84px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  border-bottom: 1px solid rgba(17, 44, 58, 0.1);
}
.brand { display: inline-flex; align-items: center; gap: 11px; width: max-content; letter-spacing: 0.12em; font-size: 14px; }
.brand svg { width: 34px; fill: none; stroke: var(--cyan-deep); stroke-width: 2.3; stroke-linecap: round; }
.brand b { font-weight: 800; }
.brand span { white-space: nowrap; }
.site-header nav { display: flex; gap: 36px; font-size: 13px; font-weight: 650; }
.site-header nav a { position: relative; }
.site-header nav a::after { content: ""; position: absolute; left: 0; right: 100%; bottom: -10px; height: 2px; background: var(--cyan); transition: right .2s ease; }
.site-header nav a:hover::after { right: 0; }
.page-mark { justify-self: end; font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 12px; letter-spacing: .08em; }
.page-mark span { color: #84979f; margin-right: 9px; }

.hero, .concepts { width: min(1180px, calc(100% - 48px)); margin: 0 auto; }
.hero { padding: 76px 0 64px; }
.eyebrow, .section-kicker { margin: 0; color: #2e6972; font-size: 11px; font-weight: 800; letter-spacing: .18em; text-transform: uppercase; }
.eyebrow { display: flex; align-items: center; gap: 11px; }
.eyebrow span { width: 28px; height: 2px; background: var(--cyan); }
.hero-grid { display: grid; grid-template-columns: 1.35fr .65fr; gap: 90px; align-items: end; margin-top: 26px; }
h1 { margin: 0; max-width: 790px; font-size: clamp(46px, 6vw, 82px); line-height: 1.05; letter-spacing: -.055em; font-weight: 760; }
h1 span { color: var(--cyan-deep); position: relative; white-space: nowrap; }
h1 span::after { content: ""; position: absolute; height: 6px; left: 2px; right: 0; bottom: -3px; background: var(--orange); opacity: .85; transform: rotate(-1deg); }
.hero-copy { max-width: 730px; margin: 32px 0 0; color: var(--muted); font-size: 17px; line-height: 1.9; }
.hero-copy strong { color: var(--ink); font-weight: 750; }
.hero-aside { padding-bottom: 4px; }
.aside-item { display: grid; grid-template-columns: 34px 1fr auto; gap: 12px; align-items: center; }
.aside-number { width: 30px; height: 30px; display: grid; place-items: center; color: #7a8e96; border: 1px solid #c9d6d9; border-radius: 50%; font: 10px ui-monospace, monospace; }
.aside-item div { display: flex; flex-direction: column; gap: 4px; }
.aside-item small { color: #86989f; font-size: 11px; }
.aside-item strong { font-size: 13px; }
.aside-item > b { font-size: 15px; }
.cyan { color: var(--cyan-deep); } .orange { color: var(--orange); }
.aside-divider { height: 34px; border-left: 1px dashed #bccbce; margin: 7px 0 7px 15px; }

.lab-shell {
  width: min(1280px, calc(100% - 32px));
  margin: 0 auto;
  padding: 32px;
  background: var(--white);
  border: 1px solid rgba(17, 44, 58, 0.09);
  box-shadow: var(--shadow);
}
.lab-heading, .concept-heading { display: flex; align-items: end; justify-content: space-between; padding: 2px 2px 24px; }
.lab-heading h2, .concept-heading h2 { margin: 6px 0 0; font-size: 26px; letter-spacing: -.025em; }
.lab-heading > p, .concept-heading > p { max-width: 420px; margin: 0; color: #73878f; font-size: 13px; }
.control-bar { min-height: 78px; padding: 13px 16px 13px 20px; display: flex; align-items: center; gap: 28px; background: #edf3f4; border: 1px solid #dce7e9; }
.control-group { display: flex; align-items: center; gap: 15px; }
.control-label { color: #72878f; font-size: 11px; font-weight: 750; letter-spacing: .08em; }
.segmented { display: flex; padding: 4px; background: #dce7e9; border-radius: 4px; }
.mode-button { padding: 9px 17px; border: 0; border-radius: 3px; color: #657b84; background: transparent; font-size: 12px; font-weight: 700; cursor: pointer; transition: .2s ease; }
.mode-button.active { color: var(--ink); background: white; box-shadow: 0 3px 10px rgba(24, 60, 71, .1); }
.time-display { display: flex; flex-direction: column; gap: 3px; padding-left: 28px; border-left: 1px solid #cddbdd; }
.time-display span { color: #7b8e95; font-size: 10px; letter-spacing: .08em; }
.time-display strong { min-width: 104px; color: var(--ink); font: 700 14px ui-monospace, SFMono-Regular, monospace; }
.playback-controls { display: flex; align-items: center; gap: 8px; margin-left: auto; }
.speed-control { display: grid; grid-template-columns: auto 82px 36px; gap: 8px; align-items: center; margin-right: 12px; color: #758991; font-size: 10px; }
.speed-control input { width: 82px; accent-color: var(--cyan-deep); cursor: pointer; }
.speed-control output { color: var(--ink); font: 700 11px ui-monospace, monospace; }
.icon-button, .play-button { height: 44px; border: 0; cursor: pointer; }
.icon-button { width: 44px; display: grid; place-items: center; background: white; border: 1px solid #d3e0e2; }
.icon-button svg { width: 19px; fill: none; stroke: #536b75; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.play-button { min-width: 102px; display: flex; align-items: center; justify-content: center; gap: 8px; color: white; background: var(--ink); font-size: 12px; font-weight: 750; }
.play-button:hover { background: #1b4556; }
.play-button svg { width: 17px; fill: none; stroke: currentColor; stroke-width: 2.2; stroke-linecap: round; stroke-linejoin: round; }
.play-button .play-icon { display: none; fill: currentColor; stroke: none; }
.play-button.paused .play-icon { display: block; }
.play-button.paused .pause-icon { display: none; }

.insight-banner { margin-top: 14px; padding: 11px 16px; display: flex; align-items: center; gap: 11px; color: #3b5d68; background: rgba(0, 200, 208, .07); border-left: 3px solid var(--cyan); transition: .25s ease; }
.insight-banner svg { flex: 0 0 19px; width: 19px; fill: none; stroke: var(--cyan-deep); stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.insight-banner p { margin: 0; font-size: 12px; line-height: 1.6; }
.insight-banner strong { color: var(--ink); }
.insight-banner.steady { background: rgba(255, 116, 73, .075); border-left-color: var(--orange); }
.insight-banner.steady svg { stroke: var(--orange); }

.visual-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-top: 14px; }
.visual-panel { min-width: 0; border: 1px solid #d8e4e6; background: white; overflow: hidden; }
.visual-panel > header { height: 74px; display: grid; grid-template-columns: 40px 1fr auto; gap: 13px; align-items: center; padding: 0 16px; border-bottom: 1px solid #dce6e8; }
.panel-index { width: 36px; height: 36px; display: grid; place-items: center; color: white; font: 800 12px ui-monospace, monospace; }
.cyan-bg { background: var(--cyan-deep); } .orange-bg { background: var(--orange); }
.visual-panel header p { margin: 0 0 4px; color: #82959c; font-size: 9px; letter-spacing: .14em; }
.visual-panel h3 { margin: 0; font-size: 15px; }
.visual-panel h3 span { color: #7b8e95; font-size: 11px; font-weight: 500; }
.status-chip { display: flex; align-items: center; gap: 6px; padding: 6px 9px; color: #34717a; background: #e8f6f6; font-size: 9px; border-radius: 999px; }
.status-chip i { width: 6px; height: 6px; background: var(--cyan-deep); border-radius: 50%; box-shadow: 0 0 0 3px rgba(0, 168, 177, .12); }
.orange-status { color: #a85134; background: #fff0eb; }
.orange-status i { background: var(--orange); box-shadow: 0 0 0 3px rgba(255, 116, 73, .12); animation: pulse 1.5s infinite; }
@keyframes pulse { 50% { box-shadow: 0 0 0 6px rgba(255, 116, 73, 0); } }
.canvas-wrap { position: relative; height: 375px; overflow: hidden; background: var(--navy); }
canvas { width: 100%; height: 100%; display: block; }
.canvas-note { position: absolute; padding: 7px 9px; color: #a9c3cb; background: rgba(6, 29, 39, .76); border: 1px solid rgba(153, 200, 210, .18); backdrop-filter: blur(5px); font: 9px ui-monospace, monospace; pointer-events: none; }
.canvas-note b { color: white; }
.top-note { top: 12px; left: 12px; }
.comparison-note { position: absolute; right: 12px; top: 13px; display: flex; align-items: center; gap: 6px; color: rgba(190, 224, 228, .62); font-size: 8px; pointer-events: none; }
.comparison-note i { width: 17px; height: 1px; border-top: 1px dashed var(--cyan); }
.axis-label { position: absolute; color: rgba(199, 228, 232, .45); font: italic 11px Georgia, serif; pointer-events: none; }
.axis-y { left: 9px; top: 45px; }
.axis-x { right: 11px; bottom: 9px; }
.flow-direction { position: absolute; right: 13px; top: 13px; color: rgba(192, 224, 228, .52); font-size: 9px; letter-spacing: .06em; pointer-events: none; }
.flow-direction span { color: var(--cyan); font-size: 15px; margin-left: 4px; }
.particle-callout { position: absolute; display: none; padding: 5px 7px; color: white; background: var(--orange); font-size: 8px; font-weight: 750; pointer-events: none; transform: translate(15px, -34px); white-space: nowrap; }
.visual-panel > footer { min-height: 62px; display: flex; align-items: center; gap: 12px; padding: 12px 16px; background: #f8fafa; }
.visual-panel footer p { margin: 0; color: #607780; font-size: 11px; line-height: 1.6; }
.visual-panel footer strong { color: var(--ink); }
.line-swatch { width: 33px; flex: 0 0 33px; height: 2px; position: relative; }
.line-swatch::after { content: ""; position: absolute; right: -1px; top: -2px; width: 6px; height: 6px; border-radius: 50%; }
.cyan-line { background: var(--cyan); }.cyan-line::after { background: var(--cyan); }
.orange-line { background: var(--orange); }.orange-line::after { background: var(--orange); }
.lab-legend { display: flex; align-items: center; justify-content: center; gap: 30px; padding: 18px 0 0; color: #70858d; font-size: 9px; }
.lab-legend > span { display: inline-flex; align-items: center; gap: 7px; }
.legend-arrow { color: #6e949c; font-size: 15px; font-style: normal; }
.legend-line-cyan, .legend-line-orange { width: 22px; height: 2px; background: var(--cyan); }
.legend-line-orange { background: var(--orange); }
.legend-dot { width: 8px; height: 8px; border: 2px solid var(--orange); border-radius: 50%; box-shadow: 0 0 0 2px rgba(255,116,73,.2); }

.concepts { padding: 110px 0 100px; }
.concept-heading { padding: 0 0 42px; }
.question-grid { display: grid; grid-template-columns: 1fr 70px 1fr; align-items: stretch; }
.question-card { position: relative; min-height: 330px; padding: 38px 42px 34px; background: white; border-top: 3px solid; box-shadow: 0 14px 45px rgba(25, 59, 69, .06); }
.cyan-card { border-color: var(--cyan); } .orange-card { border-color: var(--orange); }
.question-icon { position: absolute; right: 29px; top: 29px; width: 58px; height: 58px; display: grid; place-items: center; border-radius: 50%; }
.cyan-card .question-icon { background: #e7f8f8; color: var(--cyan-deep); }
.orange-card .question-icon { background: #fff0eb; color: var(--orange); }
.question-icon svg { width: 32px; fill: none; stroke: currentColor; stroke-width: 1.7; stroke-linecap: round; }
.question-card small { color: #8a9ca3; font-size: 10px; font-weight: 800; letter-spacing: .12em; }
.question-card h3 { max-width: 330px; margin: 19px 0 16px; font-size: 22px; line-height: 1.45; letter-spacing: -.02em; }
.question-card p { max-width: 430px; margin: 0; color: #657b84; font-size: 13px; line-height: 1.85; }
.formula { min-height: 48px; margin-top: 26px; padding: 10px 15px; display: flex; align-items: center; justify-content: center; gap: 8px; color: #21515b; background: #edf7f7; font: italic 14px Georgia, serif; }
.formula span { display: inline-block; } .formula b { color: #97acb1; } .formula strong { color: var(--cyan-deep); font-size: 18px; margin: 0 4px; }
.orange-card .formula { background: #fff3ef; color: #794635; }
.formula.stacked { gap: 24px; font-size: 13px; }
.versus { display: grid; place-items: center; position: relative; }
.versus i { position: absolute; top: 0; bottom: 0; width: 1px; border-left: 1px dashed #c6d4d7; }
.versus span { z-index: 1; width: 42px; height: 42px; display: grid; place-items: center; color: white; background: var(--ink); border-radius: 50%; font: 800 10px ui-monospace, monospace; box-shadow: 0 0 0 8px var(--paper); }
.comparison-table { margin-top: 46px; border: 1px solid #d5e1e3; background: white; }
.table-row { min-height: 58px; display: grid; grid-template-columns: .7fr 1.25fr 1.25fr; border-bottom: 1px solid #e0e9ea; }
.table-row:last-child { border-bottom: 0; }
.table-row > div { display: flex; align-items: center; padding: 13px 24px; border-right: 1px solid #e0e9ea; color: #526b75; font-size: 12px; }
.table-row > div:last-child { border-right: 0; }
.table-row > div:first-child { color: #748990; font-size: 10px; font-weight: 750; letter-spacing: .08em; }
.table-head { min-height: 48px; background: var(--navy); }
.table-head > div { color: #d7e5e8 !important; border-right-color: rgba(255,255,255,.1); font-size: 9px !important; letter-spacing: .1em; }
.cyan-dot, .orange-dot { width: 7px; height: 7px; margin-right: 9px; background: var(--cyan); border-radius: 50%; }
.orange-dot { background: var(--orange); }
.highlight-row { background: linear-gradient(90deg, rgba(0,200,208,.06), rgba(255,116,73,.06)); }
.highlight-row > div:not(:first-child) { color: var(--ink); font-weight: 800; }
.takeaway { min-height: 102px; margin-top: 28px; padding: 20px 24px; display: grid; grid-template-columns: 48px 1fr auto; align-items: center; gap: 20px; color: white; background: var(--navy); }
.takeaway-mark { width: 44px; height: 44px; display: grid; place-items: center; color: var(--navy); background: var(--cyan); font: 800 22px Georgia, serif; border-radius: 50%; }
.takeaway small { color: #7fb2ba; font-size: 9px; font-weight: 800; letter-spacing: .16em; }
.takeaway p { margin: 7px 0 0; color: #c8dadd; font-size: 13px; }
.takeaway p strong { color: white; }
.takeaway button { padding: 11px 15px; color: white; background: transparent; border: 1px solid rgba(255,255,255,.2); font-size: 11px; cursor: pointer; }
.takeaway button:hover { border-color: var(--cyan); color: var(--cyan); }
.takeaway button span { margin-left: 8px; }
.site-footer { width: min(1280px, calc(100% - 48px)); min-height: 86px; margin: 0 auto; display: flex; justify-content: space-between; align-items: center; color: #83969d; border-top: 1px solid #d4e0e2; font: 9px ui-monospace, monospace; letter-spacing: .09em; }

.style-preview { position: fixed; z-index: 50; right: 18px; bottom: 18px; display: flex; align-items: center; gap: 10px; padding: 7px; color: var(--ink); background: rgba(255,255,255,.9); border: 1px solid var(--line); border-radius: 10px; box-shadow: 0 12px 36px rgba(10,34,44,.16); backdrop-filter: blur(12px); }
.style-preview > span { padding-left: 7px; color: var(--muted); font: 700 9px ui-monospace, monospace; letter-spacing: .1em; }
.style-preview div { display: flex; gap: 4px; }
.style-preview button { padding: 7px 10px; color: var(--muted); background: transparent; border: 0; border-radius: 6px; font-size: 11px; font-weight: 700; cursor: pointer; }
.style-preview button:hover { color: var(--ink); background: var(--paper); }
.style-preview button.active { color: white; background: var(--ink); }

@media (max-width: 980px) {
  .hero-grid { grid-template-columns: 1fr; gap: 50px; }
  .hero-aside { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
  .aside-divider { display: none; }
  .control-bar { flex-wrap: wrap; }
  .playback-controls { width: 100%; margin-left: 0; padding-top: 12px; border-top: 1px solid #d6e2e4; }
  .visual-grid { grid-template-columns: 1fr; }
  .canvas-wrap { height: 420px; }
}
@media (max-width: 720px) {
  .site-header { width: calc(100% - 32px); grid-template-columns: 1fr auto; height: 68px; }
  .site-header nav { display: none; }
  .hero { width: calc(100% - 32px); padding: 54px 0 46px; }
  h1 { font-size: clamp(42px, 13vw, 64px); }
  .hero-copy { font-size: 15px; }
  .hero-aside { grid-template-columns: 1fr; }
  .lab-shell { width: calc(100% - 16px); padding: 12px; }
  .lab-heading, .concept-heading { align-items: start; flex-direction: column; gap: 12px; }
  .control-bar { padding: 14px; gap: 14px; }
  .control-group { width: 100%; justify-content: space-between; }
  .segmented { flex: 1; }
  .mode-button { flex: 1; }
  .time-display { padding-left: 0; border-left: 0; }
  .speed-control { margin-right: auto; grid-template-columns: auto 70px 33px; }
  .play-button { min-width: 80px; }
  .canvas-wrap { height: 330px; }
  .visual-panel > header { grid-template-columns: 36px 1fr; padding: 0 12px; }
  .status-chip { display: none; }
  .lab-legend { flex-wrap: wrap; gap: 12px 20px; justify-content: start; }
  .concepts { width: calc(100% - 32px); padding: 80px 0; }
  .question-grid { grid-template-columns: 1fr; gap: 20px; }
  .versus { display: none; }
  .question-card { padding: 32px 26px; }
  .question-card h3 { padding-right: 55px; }
  .comparison-table { overflow-x: auto; }
  .table-row { min-width: 620px; }
  .takeaway { grid-template-columns: 42px 1fr; }
  .takeaway button { grid-column: 1 / -1; }
  .site-footer { width: calc(100% - 32px); flex-direction: column; justify-content: center; gap: 8px; text-align: center; }
  .style-preview { right: 8px; bottom: 8px; left: 8px; justify-content: space-between; overflow-x: auto; }
  .style-preview > span { display: none; }
  .style-preview div { width: 100%; }
  .style-preview button { flex: 1; white-space: nowrap; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; }
}