/* 2020s: cool neutrals, generous space, plain liquid-glass panels over drifting bubbles (parallax), blues and
   purples with one neon green accent. Flat glass, no 3D shading. A working dark mode. */
html[data-decade="2020s"] .stage {
  --bg: #eef1f7; --text: #12141c; --muted: #5b6274; --line: rgba(255, 255, 255, .75);
  --glass: rgba(255, 255, 255, .5); --glass-edge: rgba(255, 255, 255, .8); --shadow: rgba(40, 52, 110, .08);
  --blue: #3b82f6; --indigo: #5b5bf0; --purple: #9b6cf6; --sky: #8fb8ff; --neon: #39ff9f; --accent: #5b5bf0;
  background: var(--bg); color: var(--text);
}
html[data-decade="2020s"] .stage.is-dark {
  --bg: #0b0d14; --text: #f2f4fa; --muted: #a3a9ba; --line: rgba(255, 255, 255, .12);
  --glass: rgba(24, 28, 42, .5); --glass-edge: rgba(255, 255, 255, .14); --shadow: rgba(0, 0, 0, .35);
  --blue: #3b6fe0; --indigo: #5a52e8; --purple: #8a5cf0; --sky: #3c5fb0; --neon: #39ff9f; --accent: #a5a6ff;
}
html[data-decade="2020s"] body { background: #eef1f7; }
html[data-decade="2020s"] .site { position: relative; font: 18px/1.7 system-ui, -apple-system, "Segoe UI", Roboto, "Inter", sans-serif; max-width: 1120px; margin: 0 auto; padding: 0 24px 120px; }
html[data-decade="2020s"] .site > :not(.abstract) { position: relative; z-index: 1; }

/* Background: soft colour fields and glass bubbles on a fixed layer; app.js moves each at its own depth on scroll. */
html[data-decade="2020s"] .abstract { position: fixed; inset: var(--machine-h) 0 0 0; z-index: 0; pointer-events: none; overflow: hidden; }
html[data-decade="2020s"] .abstract span { position: absolute; display: block; border-radius: 50%; will-change: transform; }
html[data-decade="2020s"] .field { filter: blur(60px); opacity: .55; }
html[data-decade="2020s"] .field-a { width: 520px; height: 520px; right: -80px; top: -60px; background: var(--purple); }
html[data-decade="2020s"] .field-b { width: 460px; height: 460px; left: -140px; top: 380px; background: var(--blue); opacity: .4; }
html[data-decade="2020s"] .field-c { width: 180px; height: 180px; right: 22%; top: 300px; background: var(--neon); opacity: .35; }
html[data-decade="2020s"] .bubble { background: rgba(255, 255, 255, .14); border: 1px solid rgba(255, 255, 255, .7); backdrop-filter: blur(6px) saturate(1.5); -webkit-backdrop-filter: blur(6px) saturate(1.5); }
html[data-decade="2020s"] .stage.is-dark .bubble { background: rgba(255, 255, 255, .04); border-color: rgba(255, 255, 255, .18); }
html[data-decade="2020s"] .bubble-1 { width: 240px; height: 240px; right: 10%; top: 60px; }
html[data-decade="2020s"] .bubble-2 { width: 120px; height: 120px; right: 34%; top: 230px; }
html[data-decade="2020s"] .bubble-3 { width: 70px; height: 70px; right: 6%; top: 380px; }
html[data-decade="2020s"] .bubble-4 { width: 180px; height: 180px; left: 4%; top: 640px; }
html[data-decade="2020s"] .bubble-5 { width: 90px; height: 90px; left: 46%; top: 820px; }
html[data-decade="2020s"] .bubble-6 { width: 140px; height: 140px; right: 8%; top: 1040px; }

html[data-decade="2020s"] .site-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 24px; padding: 120px 0 48px; min-height: 440px; }
html[data-decade="2020s"] .site-title { margin: 0; max-width: 11ch; font-size: clamp(44px, 8vw, 104px); font-weight: 700; letter-spacing: -0.045em; line-height: .95; }
html[data-decade="2020s"] .site-tagline { margin: 28px 0 0; max-width: 34ch; color: var(--muted); font-size: 20px; }
html[data-decade="2020s"] .mode-toggle { font: inherit; font-size: 14px; padding: 10px 16px; border-radius: 999px; border: 1px solid var(--glass-edge); background: var(--glass); backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px); color: var(--text); cursor: pointer; white-space: nowrap; }
html[data-decade="2020s"] .mode-toggle:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

html[data-decade="2020s"] .site-nav ul { list-style: none; margin: 0 0 16px; padding: 0; display: flex; flex-wrap: wrap; gap: 10px; }
html[data-decade="2020s"] .site-nav a { display: block; white-space: nowrap; padding: 10px 18px; border-radius: 999px; background: var(--glass); border: 1px solid var(--glass-edge); backdrop-filter: blur(16px) saturate(1.6); -webkit-backdrop-filter: blur(16px) saturate(1.6); color: var(--text); text-decoration: none; font-size: 15px; }
html[data-decade="2020s"] .site-nav a:hover { border-color: var(--accent); }

html[data-decade="2020s"] .site-main { display: grid; grid-template-columns: repeat(6, 1fr); gap: 32px; padding-top: 48px; }
/* Liquid glass: translucent, blurred, lit at the edge, no bevels or drop-shadow depth. */
html[data-decade="2020s"] .card {
  position: relative; overflow: hidden; grid-column: span 3; border-radius: 28px; padding: 44px;
  background: var(--glass); border: 1px solid var(--glass-edge); box-shadow: 0 12px 40px var(--shadow), inset 0 1px 0 var(--glass-edge);
  backdrop-filter: blur(22px) saturate(1.7); -webkit-backdrop-filter: blur(22px) saturate(1.7);
}
html[data-decade="2020s"] .card--practices { grid-column: 1 / -1; }
html[data-decade="2020s"] .card-title { font-size: 26px; letter-spacing: -0.02em; line-height: 1.2; margin: 0 0 18px; }
html[data-decade="2020s"] .card p, html[data-decade="2020s"] .card dd, html[data-decade="2020s"] .card li { color: var(--muted); }
html[data-decade="2020s"] .card p { margin: 0 0 18px; }
html[data-decade="2020s"] .card strong { color: var(--text); font-weight: 600; }
html[data-decade="2020s"] .stat { margin: 0 0 24px; }
html[data-decade="2020s"] .stat-value { display: inline-block; font-size: 64px; font-weight: 700; letter-spacing: -0.04em; line-height: 1; color: var(--indigo); padding-bottom: 6px; background: linear-gradient(var(--neon), var(--neon)) left bottom / 100% 4px no-repeat; }
html[data-decade="2020s"] .stage.is-dark .stat-value { color: var(--accent); }
html[data-decade="2020s"] .stat-label { color: var(--muted); font-size: 15px; margin-top: 10px; }
html[data-decade="2020s"] .terms { display: grid; grid-template-columns: max-content 1fr; gap: 10px 24px; margin: 24px 0 0; }
html[data-decade="2020s"] .terms dt { color: var(--text); font-weight: 600; }
html[data-decade="2020s"] .terms dd { margin: 0; }
html[data-decade="2020s"] .uses { list-style: none; padding: 0; margin: 20px 0 0; }
html[data-decade="2020s"] .uses li { position: relative; padding-left: 20px; margin-bottom: 8px; }
html[data-decade="2020s"] .uses li::before { content: ""; position: absolute; left: 0; top: .62em; width: 8px; height: 8px; border-radius: 50%; background: var(--indigo); box-shadow: 0 0 0 3px rgba(57, 255, 159, .35); }
html[data-decade="2020s"] .site-foot { color: var(--muted); font-size: 14px; padding-top: 64px; }
html[data-decade="2020s"] a { color: var(--accent); }

@media (max-width: 860px) {
  html[data-decade="2020s"] .site { padding: 0 16px 96px; }
  html[data-decade="2020s"] .site-head { padding: 72px 0 32px; min-height: 0; flex-direction: column-reverse; }
  html[data-decade="2020s"] .bubble-1 { width: 150px; height: 150px; right: -20px; top: 20px; }
  html[data-decade="2020s"] .bubble-2, html[data-decade="2020s"] .bubble-5 { display: none; }
  html[data-decade="2020s"] .site-main { grid-template-columns: 1fr; gap: 20px; }
  html[data-decade="2020s"] .card, html[data-decade="2020s"] .card--practices { grid-column: 1 / -1; padding: 28px 24px; }
  html[data-decade="2020s"] .terms { grid-template-columns: 1fr; gap: 4px; }
  html[data-decade="2020s"] .terms dd { margin-bottom: 10px; }
}