/* ============================================================
   NEBULA ARCHIVE · base.css
   设计令牌 / 重置 / 排版 / 固定导航 / 页脚 / 按钮 / 滚动条
   ============================================================ */

:root {
  /* 冻结色板（施工文档 §2） */
  --bg: #05070f;
  --bg2: #0a0f1e;
  --wood: #3a2a1c;
  --cyan: #4fd8ff;
  --amber: #ffb454;
  --magenta: #ff4f9a;
  --star: #e8ecf8;
  --success: #3ddc84;
  --warning: #ffb454;
  --danger: #ff5470;
  --info: #4fd8ff;

  /* 派生表面 / 中性层（暖冷分离：背景冷、书架暖） */
  --surface: #0b1124;
  --surface-2: #101a36;
  --overlay: rgba(5, 7, 15, 0.82);
  --scrim: rgba(5, 7, 15, 0.6);
  --line: rgba(232, 236, 248, 0.14);
  --line-strong: rgba(232, 236, 248, 0.28);
  --text: #e8ecf8;
  --text-dim: #9aa6c4;
  --text-faint: #67739a;
  --wood-hi: #5c4327;
  --wood-lo: #241a10;

  /* 字体 */
  --font-serif: "Noto Serif SC", "Songti SC", "STSong", "SimSun", serif;
  --font-sans: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: ui-monospace, "SF Mono", "Cascadia Mono", "JetBrains Mono", Consolas, monospace;

  /* 布局 */
  --nav-h: 64px;
  --wrap: 1200px;
  --radius: 14px;
  --radius-sm: 8px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);

  /* 每页可覆写的藏书主色（detail.js / 详情页内联 --accent） */
  --accent: var(--cyan);

  color-scheme: dark;
}

/* ---------- 重置 ---------- */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 16px);
  -webkit-text-size-adjust: 100%;
}

body {
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  overflow-x: hidden;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

img, canvas, svg, video { display: block; max-width: 100%; }
input, button, select, textarea { font: inherit; color: inherit; }
a { color: var(--cyan); text-decoration: none; }
a:hover { text-decoration: none; }
ul, ol { padding: 0; list-style: none; }
[hidden] { display: none !important; }

::selection { background: rgba(79, 216, 255, 0.32); color: var(--star); }

/* ---------- 主题化滚动条 ---------- */
html { scrollbar-color: var(--wood-hi) var(--bg2); scrollbar-width: thin; }
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--bg2); }
::-webkit-scrollbar-thumb {
  background: linear-gradient(180deg, var(--wood-hi), var(--wood));
  border-radius: 6px;
  border: 2px solid var(--bg2);
}
::-webkit-scrollbar-thumb:hover {
  background: linear-gradient(180deg, var(--cyan), #2b7f9e);
}
::-webkit-scrollbar-corner { background: var(--bg2); }

/* ---------- 排版 ---------- */
h1, h2, h3, h4 {
  font-family: var(--font-serif);
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: 0.02em;
  text-wrap: balance;
}
h1 { font-size: clamp(2.1rem, 5vw, 3.6rem); }
h2 { font-size: clamp(1.4rem, 2.6vw, 2rem); }
h3 { font-size: 1.15rem; }
p { text-wrap: pretty; }

.wrap { width: min(var(--wrap), 100% - 2.5rem); margin-inline: auto; }

.kicker {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.42em;
  text-transform: uppercase;
  color: var(--cyan);
}

.mono { font-family: var(--font-mono); }
.dim { color: var(--text-dim); }

:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
  border-radius: 4px;
}

.skip-link {
  position: fixed;
  top: -60px;
  left: 12px;
  z-index: 300;
  padding: 8px 16px;
  background: var(--surface-2);
  border: 1px solid var(--cyan);
  border-radius: var(--radius-sm);
  color: var(--star);
  transition: top 0.2s var(--ease);
}
.skip-link:focus { top: 12px; }

/* ---------- 深空背景层（全站共享） ---------- */
.cosmos {
  position: fixed;
  inset: 0;
  z-index: -2;
  pointer-events: none;
  background:
    radial-gradient(1100px 620px at 78% -10%, rgba(255, 79, 154, 0.10), transparent 62%),
    radial-gradient(900px 560px at 12% 8%, rgba(79, 216, 255, 0.11), transparent 60%),
    radial-gradient(1200px 800px at 50% 118%, rgba(58, 42, 28, 0.5), transparent 66%),
    linear-gradient(180deg, var(--bg) 0%, var(--bg2) 58%, #070a16 100%);
}
.cosmos::before {
  /* 星野：双层错位星点 */
  content: "";
  position: absolute;
  inset: -50%;
  background-image:
    radial-gradient(1px 1px at 22% 31%, rgba(232, 236, 248, 0.9) 50%, transparent 51%),
    radial-gradient(1px 1px at 68% 12%, rgba(232, 236, 248, 0.7) 50%, transparent 51%),
    radial-gradient(1.5px 1.5px at 45% 64%, rgba(79, 216, 255, 0.8) 50%, transparent 51%),
    radial-gradient(1px 1px at 84% 48%, rgba(255, 180, 84, 0.75) 50%, transparent 51%),
    radial-gradient(1px 1px at 12% 78%, rgba(232, 236, 248, 0.6) 50%, transparent 51%),
    radial-gradient(1.5px 1.5px at 91% 83%, rgba(255, 79, 154, 0.6) 50%, transparent 51%),
    radial-gradient(1px 1px at 37% 90%, rgba(232, 236, 248, 0.65) 50%, transparent 51%),
    radial-gradient(1px 1px at 58% 40%, rgba(232, 236, 248, 0.5) 50%, transparent 51%);
  background-size: 520px 520px;
  animation: star-drift 160s linear infinite;
  opacity: 0.75;
}
.cosmos::after {
  /* 细颗粒噪点，压住大面积渐变的塑料感 */
  content: "";
  position: absolute;
  inset: 0;
  background-image: radial-gradient(rgba(232, 236, 248, 0.045) 1px, transparent 1.4px);
  background-size: 3px 3px;
  mix-blend-mode: overlay;
}
@keyframes star-drift {
  from { transform: translate3d(0, 0, 0); }
  to { transform: translate3d(-260px, -180px, 0); }
}

/* ---------- 固定导航 ---------- */
.site-nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  background: linear-gradient(180deg, rgba(5, 7, 15, 0.92), rgba(5, 7, 15, 0.72));
  backdrop-filter: blur(14px) saturate(1.3);
  -webkit-backdrop-filter: blur(14px) saturate(1.3);
  border-bottom: 1px solid var(--line);
}
.site-nav::after {
  /* 导航底缘霓虹细线：青→琥珀→品红 */
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -1px;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--cyan) 22%, var(--amber) 55%, var(--magenta) 82%, transparent);
  opacity: 0.55;
}
.nav-inner {
  width: min(var(--wrap), 100% - 2.5rem);
  margin-inline: auto;
  display: flex;
  align-items: center;
  gap: 1.25rem;
}
.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  color: var(--star);
  font-family: var(--font-serif);
  font-weight: 900;
  font-size: 1.05rem;
  letter-spacing: 0.08em;
  white-space: nowrap;
}
.brand:hover .brand-mark { box-shadow: 0 0 14px rgba(79, 216, 255, 0.8); }
.brand-mark {
  width: 26px; height: 26px;
  flex: none;
  border-radius: 7px;
  background:
    radial-gradient(circle at 30% 30%, var(--star) 0 1.5px, transparent 2px),
    conic-gradient(from 210deg, var(--cyan), var(--magenta), var(--amber), var(--cyan));
  box-shadow: 0 0 10px rgba(79, 216, 255, 0.5);
  transition: box-shadow 0.3s var(--ease);
}
.brand small {
  font-family: var(--font-mono);
  font-weight: 400;
  font-size: 0.6rem;
  letter-spacing: 0.3em;
  color: var(--text-faint);
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  margin-left: auto;
}
.nav-links a {
  position: relative;
  padding: 0.45rem 0.85rem;
  border-radius: var(--radius-sm);
  color: var(--text-dim);
  font-size: 0.92rem;
  letter-spacing: 0.06em;
  transition: color 0.2s var(--ease), background 0.2s var(--ease);
}
.nav-links a:hover { color: var(--star); background: rgba(79, 216, 255, 0.08); }
.nav-links a[aria-current="page"] { color: var(--cyan); }
.nav-links a[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 0.85rem; right: 0.85rem; bottom: 2px;
  height: 2px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--cyan), var(--magenta));
  box-shadow: 0 0 8px rgba(79, 216, 255, 0.7);
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.7rem 1.5rem;
  border-radius: 999px;
  border: 1px solid var(--line-strong);
  background: linear-gradient(135deg, rgba(79, 216, 255, 0.16), rgba(255, 79, 154, 0.12));
  color: var(--star);
  font-size: 0.95rem;
  letter-spacing: 0.08em;
  cursor: pointer;
  transition: transform 0.2s var(--ease), box-shadow 0.25s var(--ease), border-color 0.2s var(--ease);
}
.btn:hover {
  transform: translateY(-2px);
  border-color: var(--cyan);
  box-shadow: 0 6px 24px rgba(79, 216, 255, 0.28);
}
.btn:active { transform: translateY(0); }
.btn-primary {
  border-color: rgba(79, 216, 255, 0.65);
  background: linear-gradient(135deg, rgba(79, 216, 255, 0.28), rgba(79, 216, 255, 0.1));
  box-shadow: 0 0 18px rgba(79, 216, 255, 0.18);
}
.btn-ghost { background: transparent; }

/* ---------- 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: 5rem;
  border-top: 1px solid var(--line);
  background:
    radial-gradient(700px 220px at 50% 0%, rgba(58, 42, 28, 0.35), transparent 70%),
    linear-gradient(180deg, transparent, rgba(10, 15, 30, 0.85));
}
.footer-inner {
  width: min(var(--wrap), 100% - 2.5rem);
  margin-inline: auto;
  padding: 2.4rem 0 2.8rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1rem 2rem;
}
.footer-brand {
  font-family: var(--font-serif);
  font-weight: 700;
  letter-spacing: 0.1em;
}
.footer-brand span { color: var(--amber); }
.footer-note { color: var(--text-faint); font-size: 0.85rem; }
.footer-meta {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  color: var(--text-faint);
}
.footer-meta b { color: var(--cyan); font-weight: 400; }

/* ---------- noscript ---------- */
.noscript-banner {
  position: relative;
  z-index: 120;
  margin: calc(var(--nav-h) + 12px) auto 0;
  width: min(var(--wrap), 100% - 2.5rem);
  padding: 1rem 1.4rem;
  border: 1px solid var(--warning);
  border-radius: var(--radius);
  background: rgba(255, 180, 84, 0.1);
  color: var(--star);
}
.noscript-banner strong { color: var(--warning); }

/* ---------- 动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ---------- 响应式导航 ---------- */
@media (max-width: 768px) {
  :root { --nav-h: 56px; }
  .brand small { display: none; }
  .nav-links a { padding: 0.4rem 0.6rem; font-size: 0.85rem; }
}
@media (max-width: 390px) {
  .brand { font-size: 0.95rem; }
  .nav-inner { gap: 0.5rem; }
}