:root {
  --paper: #eef1f8;
  --ink: #1a1f3a;
  --ink-soft: #4a5170;
  --line: #c9cfe2;
  --stage: #05060b;
  --focus: #3b5bff;
  --sans: "Segoe UI Variable Display", "SF Pro Display", "Helvetica Neue", "PingFang SC", "Microsoft YaHei UI", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root {
    --paper: #0d1020;
    --ink: #e7eaf7;
    --ink-soft: #a3aac6;
    --line: #2a3050;
    --focus: #9fb2ff;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 400 1rem/1.7 var(--sans);
  overflow-x: hidden;
}
:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; }

.top {
  display: flex; align-items: center; justify-content: space-between;
  max-width: 72rem; margin: 0 auto; padding: 1.25rem 1rem;
}
.brand { display: inline-flex; align-items: center; gap: .6rem; color: inherit; text-decoration: none; font-weight: 600; letter-spacing: .08em; }
.top-note { margin: 0; color: var(--ink-soft); font-size: .875rem; letter-spacing: .04em; }

main { max-width: 72rem; margin: 0 auto; padding: 0 1rem; }

.hero { padding: 1.5rem 0 3rem; }
.hero-text { max-width: 38rem; }
h1 {
  font-weight: 250; font-size: clamp(2.2rem, 7vw, 4.6rem); line-height: 1.12;
  letter-spacing: -.01em; margin: 0 0 1rem;
}
.lede { color: var(--ink-soft); font-size: 1.0625rem; margin: 0 0 2rem; max-width: 34em; }

.stage {
  position: relative; height: clamp(22rem, 62vh, 34rem);
  background: var(--stage); border-radius: 28px; overflow: hidden;
  touch-action: none; isolation: isolate;
}
.ambient {
  position: absolute; inset: 0; z-index: 0; opacity: .22;
  background: radial-gradient(120% 90% at 50% 0%, var(--amb, #fff4e4), transparent 60%);
  transition: background .8s ease;
}
.lamp {
  --r: clamp(8rem, 30vw, 15rem);
  position: absolute; left: var(--x); top: var(--y); z-index: 1;
  width: var(--r); height: var(--r); margin: calc(var(--r) / -2) 0 0 calc(var(--r) / -2);
  border: 0; padding: 0; border-radius: 50%; cursor: grab;
  mix-blend-mode: screen; background: transparent;
}
.lamp::before {
  content: ""; position: absolute; inset: 0; border-radius: 50%;
  background: radial-gradient(circle, var(--c) 0 48%, color-mix(in srgb, var(--c) 45%, transparent) 62%, transparent 71%);
}
.lamp::after {
  content: ""; position: absolute; left: 50%; top: 50%; width: 10px; height: 10px; margin: -5px;
  border-radius: 50%; background: #fff; opacity: .85; box-shadow: 0 0 12px #fff;
}
.lamp.r { --c: #ff0000; }
.lamp.g { --c: #00ff00; }
.lamp.b { --c: #0000ff; }
.lamp:active, .lamp.dragging { cursor: grabbing; }
.lamp:focus-visible { outline-color: #fff; outline-offset: -6px; }
.stage.glide .lamp { transition: left .9s cubic-bezier(.2,.8,.2,1), top .9s cubic-bezier(.2,.8,.2,1); }

.readout {
  position: absolute; left: 1rem; bottom: 1rem; right: 1rem; z-index: 2; margin: 0;
  color: #f2f3fa; font-size: .9375rem; text-shadow: 0 1px 6px #000;
  pointer-events: none;
}
.stage-tools { display: flex; flex-wrap: wrap; gap: .6rem; margin-top: 1rem; }
.chip {
  font: inherit; font-size: .9375rem; color: var(--ink); background: transparent;
  border: 1px solid var(--line); border-radius: 999px; padding: .45rem 1.1rem; cursor: pointer;
}
.chip:hover { border-color: var(--ink-soft); }

h2 { font-weight: 300; font-size: clamp(1.6rem, 4vw, 2.4rem); margin: 0 0 .5rem; letter-spacing: .02em; }
.section-lede { color: var(--ink-soft); max-width: 36em; margin: 0 0 1.75rem; }

.five { padding: 2rem 0 3rem; }
.sources {
  list-style: none; margin: 0; padding: 0;
  display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 0;
  border-top: 1px solid var(--line);
}
.sources button {
  width: 100%; height: 100%; text-align: left; font: inherit; color: inherit;
  background: none; border: 0; border-right: 1px solid var(--line);
  padding: 1.25rem .9rem 1.25rem; cursor: pointer; display: grid; gap: .3rem;
  position: relative;
}
.sources li:last-child button { border-right: 0; }
.sources button::before {
  content: ""; display: block; height: 3.5rem; border-radius: 10px; margin-bottom: .6rem;
  background: linear-gradient(180deg, var(--sw), color-mix(in srgb, var(--sw) 35%, #05060b));
}
.sources button[aria-pressed="true"]::after {
  content: ""; position: absolute; left: .9rem; right: .9rem; top: -1px; height: 3px; background: var(--ink);
}
.k { font-variant-numeric: tabular-nums; font-size: .8125rem; color: var(--ink-soft); }
.n { font-size: 1.125rem; font-weight: 600; }
.d { font-size: .875rem; color: var(--ink-soft); line-height: 1.5; }

.notes { padding: 1rem 0 4rem; }
.notes dl { margin: 0; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 2rem; }
.notes dt { font-weight: 600; margin-bottom: .25rem; }
.notes dd { margin: 0; color: var(--ink-soft); }

.foot { border-top: 1px solid var(--line); }
.foot p { max-width: 72rem; margin: 0 auto; padding: 1.5rem 1rem 2rem; font-size: .875rem; color: var(--ink-soft); }

@media (max-width: 760px) {
  .sources { grid-template-columns: 1fr; }
  .sources button { border-right: 0; border-bottom: 1px solid var(--line); grid-template-columns: 3.5rem 1fr; column-gap: 1rem; align-items: center; }
  .sources button::before { grid-row: span 3; height: 3.5rem; margin: 0; }
  .sources button[aria-pressed="true"]::after { left: 0; right: auto; top: 1rem; bottom: 1rem; width: 3px; height: auto; }
  .notes dl { grid-template-columns: 1fr; gap: 1.25rem; }
  .top-note { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; }
}