:root {
  --lab-accent: #2563eb;
  --lab-accent-2: #0f766e;
  --lab-warn: #b45309;
  --lab-bg: #f8fafc;
  --lab-panel: #ffffff;
  --lab-border: #dbe3ef;
  --lab-text: #172033;
  --lab-muted: #667085;
}

.dark {
  --lab-bg: #101827;
  --lab-panel: #172033;
  --lab-border: #334155;
  --lab-text: #eef2ff;
  --lab-muted: #a5b4c7;
}

.lab-shell {
  max-width: 1120px;
  margin: 0 auto;
  padding: 32px 22px 64px;
  color: var(--lab-text);
}

.lab-topnav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 28px;
  font-size: 14px;
}

.lab-topnav a {
  color: var(--lab-accent);
  text-decoration: none;
  font-weight: 650;
}

.lab-hero {
  padding: 28px 0 20px;
  border-bottom: 1px solid var(--lab-border);
}

.lab-eyebrow {
  color: var(--lab-accent-2);
  font-weight: 700;
  letter-spacing: 0;
  margin: 0 0 8px;
}

.lab-hero h1 {
  font-size: 38px;
  line-height: 1.16;
  margin: 0;
}

.lab-hero p {
  max-width: 760px;
  color: var(--lab-muted);
  font-size: 17px;
  line-height: 1.75;
}

.lab-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin: 24px 0;
}

.lab-card,
.lab-section,
.lab-preview,
.learning-points,
.pitfall-box {
  background: var(--lab-panel);
  border: 1px solid var(--lab-border);
  border-radius: 8px;
}

.lab-card {
  padding: 18px;
  min-height: 150px;
}

.lab-card h2,
.lab-card h3 {
  margin: 0 0 10px;
  font-size: 20px;
}

.lab-card p,
.lab-section p,
.learning-points li,
.pitfall-box li {
  line-height: 1.7;
}

.lab-card a {
  display: inline-flex;
  margin-top: 8px;
  color: var(--lab-accent);
  font-weight: 700;
  text-decoration: none;
}

.lab-section {
  margin: 28px 0;
  padding: 24px;
}

.lab-section h2 {
  margin-top: 0;
  font-size: 28px;
}

.lab-section h3 {
  font-size: 21px;
  margin: 22px 0 10px;
}

.lesson-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(290px, 420px);
  gap: 18px;
  align-items: stretch;
}

.code-card {
  overflow: hidden;
  border: 1px solid var(--lab-border);
  border-radius: 8px;
  background: #0f172a;
}

.code-card h4 {
  margin: 0;
  padding: 10px 14px;
  color: #e2e8f0;
  border-bottom: 1px solid #24324c;
  font-size: 14px;
}

.code-card pre {
  margin: 0;
  padding: 16px;
  overflow: auto;
  color: #dbeafe;
  font-size: 13px;
  line-height: 1.55;
}

.lab-preview {
  padding: 16px;
  min-height: 260px;
}

.preview-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 12px;
  font-weight: 750;
}

.preview-screen {
  min-height: 150px;
  border: 1px dashed var(--lab-border);
  border-radius: 8px;
  background: linear-gradient(180deg, rgba(37, 99, 235, .08), rgba(15, 118, 110, .08));
  padding: 14px;
}

.preview-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 12px;
}

.lab-btn,
.demo-btn {
  appearance: none;
  border: 0;
  border-radius: 6px;
  background: var(--lab-accent);
  color: white;
  padding: 8px 12px;
  font-size: 13px;
  font-weight: 650;
  cursor: pointer;
}

.lab-btn.secondary {
  background: #475569;
}

.lab-btn.ghost {
  background: transparent;
  color: var(--lab-accent);
  border: 1px solid var(--lab-border);
}

.state-pill {
  display: inline-flex;
  align-items: center;
  min-height: 24px;
  padding: 2px 9px;
  border-radius: 999px;
  background: rgba(37, 99, 235, .12);
  color: var(--lab-accent);
  font-weight: 700;
  font-size: 12px;
}

.learning-points {
  margin-top: 16px;
  padding: 16px 18px;
}

.learning-points h4,
.pitfall-box h4 {
  margin: 0 0 8px;
  font-size: 16px;
}

.learning-points ul,
.pitfall-box ul {
  margin: 8px 0 0;
  padding-left: 20px;
}

.pitfall-box {
  margin-top: 16px;
  padding: 16px 18px;
  border-color: rgba(180, 83, 9, .35);
}

.chapter-upgrade {
  margin: 18px 0 28px;
  padding: 20px;
  border: 1px solid var(--lab-border);
  border-radius: 8px;
  background: var(--lab-panel);
}

.chapter-upgrade h2 {
  margin: 0 0 10px;
  font-size: 24px;
}

.chapter-upgrade p {
  line-height: 1.72;
}

.chapter-map {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin: 14px 0;
}

.chapter-step {
  border: 1px solid var(--lab-border);
  border-radius: 8px;
  padding: 12px;
  background: rgba(37, 99, 235, .06);
}

.chapter-step strong {
  display: block;
  margin-bottom: 5px;
}

.chapter-preview {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(260px, 360px);
  gap: 16px;
  margin-top: 16px;
}

.chapter-preview-screen {
  min-height: 180px;
  border: 1px dashed var(--lab-border);
  border-radius: 8px;
  padding: 16px;
  background:
    linear-gradient(180deg, rgba(248, 250, 252, .88), rgba(219, 234, 254, .55)),
    radial-gradient(circle at 20% 20%, rgba(20, 184, 166, .18), transparent 30%);
}

.dark .chapter-preview-screen {
  background:
    linear-gradient(180deg, rgba(15, 23, 42, .92), rgba(30, 41, 59, .8)),
    radial-gradient(circle at 20% 20%, rgba(20, 184, 166, .14), transparent 32%);
}

.chapter-state-line {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  border-bottom: 1px solid var(--lab-border);
  padding: 8px 0;
  font-size: 14px;
}

.chapter-state-line:last-child {
  border-bottom: 0;
}

.chapter-output {
  margin: 12px 0 0;
  min-height: 54px;
  color: var(--lab-muted);
}

.chapter-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-content: flex-start;
}

.code-learning-note {
  margin: 10px 0 18px;
  padding: 12px 14px;
  border: 1px solid rgba(15, 118, 110, .28);
  border-left: 4px solid var(--lab-accent-2);
  border-radius: 8px;
  background: rgba(15, 118, 110, .08);
}

.code-learning-note h4 {
  margin: 0 0 6px;
  font-size: 15px;
}

.code-learning-note ul {
  margin: 0;
  padding-left: 20px;
}

.code-learning-note li {
  line-height: 1.62;
}

.flow-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
  margin-top: 12px;
}

.flow-node {
  border: 1px solid var(--lab-border);
  border-radius: 8px;
  padding: 12px 8px;
  text-align: center;
  color: var(--lab-muted);
  font-size: 13px;
}

.flow-node.active {
  border-color: var(--lab-accent);
  color: var(--lab-accent);
  background: rgba(37, 99, 235, .1);
}

.phone-preview {
  max-width: 230px;
  margin: 0 auto;
  border: 10px solid #111827;
  border-radius: 28px;
  background: #f8fafc;
  color: #172033;
  min-height: 300px;
  padding: 16px;
  box-shadow: 0 18px 35px rgba(15, 23, 42, .18);
}

.phone-card {
  background: white;
  border-radius: 8px;
  padding: 12px;
  margin-bottom: 10px;
  border: 1px solid #e2e8f0;
}

.range-row {
  display: grid;
  grid-template-columns: 90px minmax(0, 1fr) 48px;
  gap: 10px;
  align-items: center;
  margin: 12px 0;
  font-size: 13px;
}

.lab-note {
  border-left: 4px solid var(--lab-accent-2);
  background: rgba(15, 118, 110, .08);
  padding: 12px 14px;
  border-radius: 6px;
  margin: 14px 0;
}

.lab-home-entry {
  margin: 24px auto 0;
  max-width: 1152px;
  padding: 0 24px 32px;
}

.lab-home-entry-inner {
  border: 1px solid var(--lab-border);
  border-radius: 8px;
  padding: 20px;
  background: var(--lab-panel);
}

.lab-home-entry h2 {
  margin: 0 0 8px;
}

.lab-home-entry p {
  margin: 0 0 12px;
  color: var(--lab-muted);
}

.anim-demo {
  border: 1px solid var(--lab-border);
  border-radius: 8px;
  padding: 14px;
  margin: 12px 0 18px;
  background: var(--lab-panel);
}

.anim-stage {
  min-height: 130px;
  border-radius: 8px;
  background: linear-gradient(135deg, rgba(37, 99, 235, .08), rgba(236, 72, 153, .08));
  border: 1px dashed var(--lab-border);
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 18px;
  overflow: hidden;
}

.anim-circle,
.anim-square,
.spring-ball {
  width: 58px;
  height: 58px;
  flex: 0 0 auto;
  transition: transform .65s cubic-bezier(.2, .8, .2, 1), opacity .65s, box-shadow .45s, filter .45s;
}

.anim-circle {
  border-radius: 50%;
  background: #2563eb;
  box-shadow: 0 12px 24px rgba(37, 99, 235, .25);
}

.anim-square {
  border-radius: 10px;
  background: #f97316;
  box-shadow: 0 12px 24px rgba(249, 115, 22, .25);
}

.spring-ball {
  border-radius: 50%;
  background: #f97316;
  cursor: grab;
}

.anim-bar {
  width: 180px;
  height: 10px;
  border-radius: 999px;
  background: rgba(100, 116, 139, .25);
  overflow: hidden;
}

.anim-bar-fill {
  width: 0;
  height: 100%;
  background: #0f766e;
  transition: width .75s ease;
}

.transition-box {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 112px;
  height: 72px;
  border-radius: 10px;
  background: #2563eb;
  color: white;
  font-weight: 800;
  transition: transform .5s ease, opacity .5s ease;
}

#particleCanvas {
  width: 100%;
  height: 220px;
  border: 1px solid var(--lab-border);
  border-radius: 8px;
  background: #0f172a;
}

.blur-demo-img {
  width: 72px;
  height: 72px;
  border-radius: 12px;
  background:
    radial-gradient(circle at 30% 30%, #facc15 0 16px, transparent 17px),
    linear-gradient(135deg, #2563eb, #22c55e);
}

.mermaid-container {
  position: relative;
  overflow-x: auto;
  padding: 44px 12px 12px;
  border: 1px solid var(--lab-border);
  border-radius: 8px;
  background: var(--lab-panel);
}

.mermaid-container svg {
  display: block;
  height: auto;
  max-width: none;
  transform-origin: top left;
}

.mermaid-container.mermaid-mindmap,
.mermaid-container.mermaid-wide {
  max-height: 72vh;
}

.mermaid-container.mermaid-mindmap svg,
.mermaid-container.mermaid-wide svg {
  min-width: 1180px;
  width: max(1180px, 100%);
}

.mermaid-toolbar {
  position: absolute;
  top: 8px;
  right: 8px;
  z-index: 2;
  display: flex;
  gap: 6px;
  padding: 4px;
  border: 1px solid var(--lab-border);
  border-radius: 8px;
  background: color-mix(in srgb, var(--lab-panel) 88%, transparent);
  backdrop-filter: blur(8px);
}

.mermaid-toolbar button {
  border: 1px solid var(--lab-border);
  border-radius: 6px;
  background: transparent;
  color: var(--lab-text);
  min-width: 34px;
  min-height: 30px;
  cursor: pointer;
  font-weight: 800;
}

.mermaid-canvas {
  overflow: auto;
  padding: 8px;
}

.mermaid-container.mermaid-expanded {
  position: fixed;
  inset: 18px;
  z-index: 9999;
  max-height: none;
  background: var(--lab-panel);
  box-shadow: 0 24px 80px rgba(15, 23, 42, .35);
}

.mermaid-container.mermaid-expanded .mermaid-canvas {
  height: calc(100vh - 96px);
}

@media (max-width: 820px) {
  .lesson-layout {
    grid-template-columns: 1fr;
  }
  .chapter-map,
  .chapter-preview {
    grid-template-columns: 1fr;
  }
  .lab-hero h1 {
    font-size: 30px;
  }
  .flow-row {
    grid-template-columns: 1fr 1fr;
  }
  .mermaid-container.mermaid-mindmap svg,
  .mermaid-container.mermaid-wide svg {
    min-width: 980px;
  }
}