:root {
  color-scheme: dark;
  --bg: #0a0c14;
  --panel: rgba(11, 15, 30, .88);
  --line: rgba(155, 170, 218, .16);
  --ink: #f1efe9;
  --soft: #939bb8;
  --gold: #e7bc58;
  --red: #ed4e3b;
  --sans: Inter, "PingFang TC", "Noto Sans TC", sans-serif;
  --serif: "Songti TC", "Noto Serif TC", STSong, serif;
}

* { box-sizing: border-box; }
html, body { width: 100%; min-height: 100%; margin: 0; overflow: hidden; background: var(--bg); }
body { color: var(--ink); font-family: var(--sans); }
body::before {
  position: fixed;
  inset: 0;
  background: radial-gradient(120vmax 90vmax at 62% 42%, rgba(38,48,82,.2), transparent 58%), radial-gradient(closest-side at 50% 120%, transparent 60%, rgba(4,5,10,.55) 100%);
  content: "";
  pointer-events: none;
}

#atlas-canvas { position: fixed; inset: 0; width: 100%; height: 100%; touch-action: none; cursor: grab; }
#atlas-canvas.dragging { cursor: grabbing; }

.atlas-tooltip {
  position: fixed;
  z-index: 8;
  display: grid;
  min-width: 150px;
  gap: 4px;
  padding: 10px 12px;
  border: 1px solid rgba(231,188,88,.22);
  border-radius: 10px;
  color: var(--ink);
  background: rgba(8,12,24,.88);
  box-shadow: 0 16px 50px rgba(0,0,0,.28);
  backdrop-filter: blur(14px);
  pointer-events: none;
}
.atlas-tooltip[hidden] { display: none; }
.atlas-tooltip strong { font: 700 .86rem var(--serif); }
.atlas-tooltip span { color: var(--soft); font-size: .63rem; }

.atlas-topbar {
  position: fixed;
  z-index: 5;
  top: 0;
  left: 0;
  display: flex;
  width: 100%;
  height: 62px;
  padding: 0 28px;
  align-items: center;
  justify-content: space-between;
  background: linear-gradient(to bottom, rgba(7,10,20,.94), transparent);
}

.atlas-wordmark { display: flex; gap: 14px; align-items: baseline; color: var(--ink); text-decoration: none; }
.atlas-wordmark b { font: 750 1.15rem var(--serif); letter-spacing: .12em; }
.atlas-wordmark span { color: var(--soft); font-size: .58rem; letter-spacing: .28em; }
.atlas-topbar nav { display: flex; gap: 6px; }
.atlas-topbar nav a { padding: 7px 10px; border-radius: 8px; color: var(--soft); font-size: .72rem; text-decoration: none; }
.atlas-topbar nav a.active { color: var(--ink); background: rgba(237,239,247,.08); font-weight: 700; }

.atlas-intro {
  position: fixed;
  z-index: 4;
  top: 92px;
  left: 40px;
  width: min(430px, 92vw);
  pointer-events: none;
}
.atlas-intro::before { display: none; }
.atlas-intro > p { margin: 0 0 17px; color: var(--gold); font-size: .69rem; font-weight: 750; letter-spacing: .16em; }
.atlas-intro h1 { margin: 0; font: 600 clamp(2.35rem, 3.6vw, 3.25rem)/1.12 var(--serif); letter-spacing: .02em; }
.atlas-intro h1 span { color: var(--red); }
.atlas-intro > strong { display: block; max-width: 390px; margin-top: 14px; color: var(--soft); font-size: .82rem; font-weight: 450; line-height: 1.75; }
.atlas-intro > strong b { color: var(--ink); }
.atlas-search { position: fixed; top: 76px; right: 28px; display: flex; width: min(280px,58vw); height: 38px; margin: 0; padding: 0 13px; gap: 9px; align-items: center; border: 1px solid var(--line); border-radius: 10px; background: rgba(13,16,26,.72); backdrop-filter: blur(12px); pointer-events: auto; }
.atlas-search span { color: var(--soft); font-size: 1.2rem; }
.atlas-search input { min-width: 0; flex: 1; border: 0; outline: 0; color: var(--ink); background: transparent; font: .78rem var(--sans); }
.atlas-search input::placeholder { color: #6d7591; }
.atlas-filters { display: flex; max-width: 350px; margin-top: 18px; gap: 2px; flex-wrap: wrap; pointer-events: auto; }
.atlas-filters button { padding: 5px 9px; border: 0; border-radius: 8px; color: var(--soft); background: transparent; font: .68rem var(--sans); cursor: pointer; }
.atlas-filters button.active { border-color: currentColor; color: var(--gold); background: rgba(231,188,88,.1); }

.atlas-detail {
  position: fixed;
  z-index: 7;
  top: 24px;
  right: 24px;
  bottom: 24px;
  width: min(330px, calc(100vw - 32px));
  max-height: none;
  padding: 24px 22px 20px;
  overflow: auto;
  border: 1px solid rgba(231,188,88,.25);
  border-radius: 16px;
  background: var(--panel);
  box-shadow: 0 28px 80px rgba(0,0,0,.42);
  backdrop-filter: blur(20px);
  animation: detail-in .25s ease both;
}
.atlas-detail[hidden] { display: none; }
.atlas-detail > button { position: absolute; top: 14px; right: 14px; width: 34px; height: 34px; border: 1px solid var(--line); border-radius: 50%; color: var(--ink); background: transparent; font-size: 1.2rem; cursor: pointer; }
.atlas-detail > p { margin: 0 0 10px; color: var(--gold); font-size: .65rem; font-weight: 800; letter-spacing: .16em; }
.atlas-detail h2 { margin: 0; padding-right: 38px; font: 800 2.1rem/1.15 var(--serif); }
#detail-description { margin: 18px 0 22px; color: var(--soft); font: .88rem/1.8 var(--serif); }
.detail-lessons { border-top: 1px solid var(--line); }
.detail-lessons a { display: grid; grid-template-columns: 58px minmax(0,1fr) auto; padding: 13px 0; gap: 10px; align-items: baseline; border-bottom: 1px solid var(--line); color: var(--ink); text-decoration: none; }
.detail-lessons a span, .detail-lessons a small { color: var(--soft); font-size: .64rem; }
.detail-lessons a b { overflow: hidden; font: 650 .85rem var(--serif); text-overflow: ellipsis; white-space: nowrap; }
.detail-lessons a:hover b { color: var(--gold); }
.detail-empty { color: var(--soft); font-size: .78rem; }

.atlas-hint { position: fixed; z-index: 3; bottom: 18px; left: 50%; color: #646c84; font-size: .66rem; letter-spacing: .06em; white-space: nowrap; pointer-events: none; transform: translateX(-50%); }

@keyframes detail-in { from { opacity: 0; transform: translateX(20px); } }

@media (max-width: 820px) {
  .atlas-topbar { height: 62px; padding: 0 16px; }
  .atlas-wordmark span { display: none; }
  .atlas-topbar nav a { padding: 7px 9px; font-size: .66rem; }
  .atlas-intro { top: 82px; left: 18px; width: calc(100vw - 36px); }
  .atlas-intro h1 { font-size: clamp(2.15rem, 11vw, 3.2rem); }
  .atlas-intro > strong { max-width: 70vw; margin-top: 12px; font-size: .72rem; line-height: 1.6; }
  .atlas-search { top: auto; right: 12px; bottom: 46px; left: 12px; width: auto; }
  .atlas-filters { width: calc(100vw - 36px); flex-wrap: nowrap; overflow-x: auto; scrollbar-width: none; }
  .atlas-filters::-webkit-scrollbar { display: none; }
  .atlas-filters button { flex: 0 0 auto; }
  .atlas-detail { top: auto; right: 8px; bottom: 96px; left: 8px; width: auto; max-width: none; max-height: 48svh; border-radius: 16px; }
  .atlas-detail h2 { font-size: 1.65rem; }
  .atlas-hint { right: auto; bottom: 14px; max-width: 94vw; font-size: .62rem; text-align: center; }
  .atlas-tooltip { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; }
}