:root {
  --bg: #f4f6f8;
  --bg-deep: #0b1f3a;
  --panel: rgba(255, 255, 255, 0.92);
  --panel-strong: rgba(255, 255, 255, 0.96);
  --panel-border: rgba(15, 23, 42, 0.1);
  --panel-shadow: 0 18px 40px rgba(15, 23, 42, 0.1);
  --text: #172033;
  --muted: #596476;
  --link: #12315c;
  --link-hover: #2f5d96;
  --accent: #12457f;
  --accent-hover: #1a5a9e;
  --accent-soft: #dde7f4;
  --accent-line: rgba(18, 69, 127, 0.14);
  --surface: rgba(11, 31, 58, 0.9);
  --surface-text: #f4f7fb;
  --radius-lg: 24px;
  --radius-md: 18px;
  --radius-sm: 12px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at top, rgba(162, 177, 199, 0.22), transparent 34%),
    var(--bg);
  color: var(--text);
  font-family: Georgia, "Times New Roman", "Noto Serif", serif;
  line-height: 1.7;
}

a {
  color: var(--link);
  text-decoration: none;
  transition: color 0.22s ease, transform 0.22s ease, box-shadow 0.22s ease;
}

a:hover {
  color: var(--link-hover);
}

button,
input,
select {
  font: inherit;
}

.demo-page {
  position: relative;
}

.full-canvas {
  position: fixed;
  inset: 0;
  z-index: -1;
  width: 100vw;
  height: 100vh;
}

.page-shell {
  width: min(1120px, calc(100% - 28px));
  margin: 0 auto;
  padding: 26px 0 48px;
}

.page-shell--overlay {
  padding-top: 32px;
}

.demo-hero {
  position: relative;
  overflow: hidden;
  margin-bottom: 28px;
  padding: 34px 32px 28px;
  border-radius: 28px;
  background: linear-gradient(140deg, rgba(12, 31, 58, 0.96), rgba(16, 51, 96, 0.9));
  box-shadow: 0 26px 54px rgba(11, 31, 58, 0.2);
  color: var(--surface-text);
}

.demo-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at top right, rgba(255, 255, 255, 0.16), transparent 30%),
    radial-gradient(circle at bottom left, rgba(255, 255, 255, 0.08), transparent 26%);
  pointer-events: none;
}

.demo-hero > * {
  position: relative;
  z-index: 1;
}

.demo-back {
  display: inline-flex;
  align-items: center;
  margin-bottom: 14px;
  color: rgba(244, 247, 251, 0.82);
  font-family: "Segoe UI", "PingFang SC", "Noto Sans", sans-serif;
  font-size: 0.92rem;
}

.demo-back:hover {
  color: #ffffff;
}

.demo-back::before {
  content: "\2190";
  margin-right: 8px;
}

.demo-title {
  margin: 0;
  color: #ffffff;
  font-family: "Segoe UI", "PingFang SC", "Noto Sans", sans-serif;
  font-size: clamp(2rem, 3.8vw, 3rem);
  font-weight: 600;
  letter-spacing: 0.01em;
  line-height: 1.12;
}

.demo-summary {
  max-width: 780px;
  margin: 16px 0 0;
  color: rgba(240, 245, 252, 0.8);
  font-size: 1rem;
}

.demo-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(300px, 0.85fr);
  gap: 24px;
  align-items: start;
}

.demo-layout--overlay {
  grid-template-columns: minmax(300px, 460px);
}

.canvas-card,
.control-card {
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-lg);
  background: var(--panel);
  box-shadow: var(--panel-shadow);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.canvas-card {
  overflow: hidden;
}

.canvas-card__frame {
  padding: 18px;
  background: var(--panel-strong);
}

.canvas-card__frame canvas {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-md);
  background: linear-gradient(180deg, #f8fafc, #e8eef6);
  border: 1px solid rgba(15, 23, 42, 0.08);
}

.control-card {
  padding: 26px 24px 24px;
}

.control-card--overlay {
  background: rgba(11, 20, 36, 0.76);
  border-color: rgba(255, 255, 255, 0.08);
  box-shadow: 0 22px 48px rgba(11, 31, 58, 0.18);
  color: var(--surface-text);
}

.control-card--overlay .section-title,
.control-card--overlay .field-label,
.control-card--overlay .inline-value,
.control-card--overlay .info-block h2,
.control-card--overlay .toggle-button,
.control-card--overlay .demo-link,
.control-card--overlay .secondary-link {
  color: inherit;
}

.control-card--overlay .field-note,
.control-card--overlay .info-block p {
  color: rgba(240, 245, 252, 0.74);
}

.control-card--overlay .range-input,
.control-card--overlay .select-input,
.control-card--overlay .button-row button,
.control-card--overlay .toggle-button {
  border-color: rgba(255, 255, 255, 0.12);
}

.section-title {
  margin: 0 0 18px;
  color: var(--bg-deep);
  font-family: "Segoe UI", "PingFang SC", "Noto Sans", sans-serif;
  font-size: 1.12rem;
  font-weight: 600;
}

.control-group + .control-group,
.info-block + .info-block {
  margin-top: 24px;
}

.field-stack {
  display: grid;
  gap: 16px;
}

.field-label {
  display: block;
  margin-bottom: 8px;
  color: var(--bg-deep);
  font-family: "Segoe UI", "PingFang SC", "Noto Sans", sans-serif;
  font-size: 0.95rem;
  font-weight: 600;
}

.inline-value {
  color: var(--accent);
}

.field-note {
  margin-top: 6px;
  color: var(--muted);
  font-size: 0.9rem;
}

.range-input,
.select-input {
  width: 100%;
  padding: 12px 14px;
  border: 1px solid var(--accent-line);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.92);
  color: var(--text);
}

.range-input {
  padding: 0;
  background: transparent;
  border: 0;
}

input[type="range"] {
  accent-color: var(--accent);
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.button-row button,
.toggle-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 88px;
  padding: 10px 16px;
  border: 1px solid var(--accent-line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.9);
  color: var(--text);
  font-family: "Segoe UI", "PingFang SC", "Noto Sans", sans-serif;
  font-size: 0.92rem;
  font-weight: 600;
  transition: background-color 0.22s ease, color 0.22s ease, transform 0.22s ease, box-shadow 0.22s ease;
}

.button-row button:hover,
.toggle-button:hover {
  transform: translateY(-1px);
  box-shadow: 0 14px 24px rgba(17, 56, 100, 0.12);
}

.button-row button.is-primary,
.toggle-button.is-active {
  background: linear-gradient(180deg, #184985, #113864);
  color: #f8fbff;
  border-color: rgba(17, 56, 100, 0.28);
}

.toggle-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.info-block {
  padding-top: 20px;
  border-top: 1px solid rgba(15, 23, 42, 0.08);
}

.info-block h2 {
  margin: 0 0 12px;
  color: var(--bg-deep);
  font-family: "Segoe UI", "PingFang SC", "Noto Sans", sans-serif;
  font-size: 1rem;
  font-weight: 600;
}

.info-block p {
  margin: 0;
  color: var(--muted);
}

.info-block p + p {
  margin-top: 10px;
}

.secondary-link,
.demo-link {
  color: var(--muted);
  font-family: "Segoe UI", "PingFang SC", "Noto Sans", sans-serif;
  font-size: 0.9rem;
}

.secondary-link:hover,
.demo-link:hover {
  color: var(--link-hover);
}

.demo-footer {
  margin-top: 18px;
  text-align: right;
}

.katex,
.katex-display {
  color: inherit;
}

@media (max-width: 900px) {
  .demo-layout,
  .demo-layout--overlay {
    grid-template-columns: 1fr;
  }

  .control-card--overlay {
    background: var(--panel);
    border-color: var(--panel-border);
    box-shadow: var(--panel-shadow);
    color: var(--text);
  }

  .control-card--overlay .section-title,
  .control-card--overlay .field-label,
  .control-card--overlay .inline-value,
  .control-card--overlay .info-block h2,
  .control-card--overlay .toggle-button,
  .control-card--overlay .demo-link,
  .control-card--overlay .secondary-link {
    color: inherit;
  }

  .control-card--overlay .field-note,
  .control-card--overlay .info-block p {
    color: var(--muted);
  }
}

@media (max-width: 640px) {
  .page-shell {
    width: min(calc(100% - 18px), 1120px);
    padding-top: 18px;
  }

  .demo-hero {
    padding: 28px 22px 24px;
    border-radius: 22px;
  }

  .control-card,
  .control-card--overlay {
    padding: 22px 18px;
    border-radius: 20px;
  }

  .canvas-card {
    border-radius: 20px;
  }

  .canvas-card__frame {
    padding: 12px;
  }
}