/* ============================================================
   Study.css v2 — 数学与物理学习体系共享样式（视觉升级）
   设计语言：深空蓝黑 + 玻璃拟态 + 电光青/霓虹粉强调
   ============================================================ */

:root {
  --bg:            #070713;
  --panel:         rgba(22,22,46,.62);
  --panel-solid:   #12122a;
  --panel-2:       rgba(34,34,66,.55);
  --border:        rgba(0,212,255,.16);
  --border-soft:   rgba(255,255,255,.07);
  --primary:       #00d4ff;
  --primary-dim:   #0a91b3;
  --accent:        #ff6b9d;
  --success:       #00ff88;
  --warning:       #ffb454;
  --text:          #e7e9f5;
  --text-dim:      #9aa0c4;
  --radius:        14px;
  --radius-sm:     9px;
  --font-title:    "Orbitron", "Microsoft YaHei", sans-serif;
  --font-body:     "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-mono:     "JetBrains Mono", "Fira Code", "Consolas", monospace;
  --shadow:        0 10px 34px rgba(0,0,0,.42);
  --glow:          0 0 22px rgba(0,212,255,.35);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 90px; }

body {
  margin: 0;
  color: var(--text);
  font-family: var(--font-body);
  line-height: 1.85;
  font-size: 15.5px;
  letter-spacing: .2px;
  background-color: var(--bg);
  background-image:
    radial-gradient(900px 620px at 86% -12%, rgba(0,212,255,.12), transparent 60%),
    radial-gradient(760px 520px at 8% 112%, rgba(255,107,157,.09), transparent 60%),
    linear-gradient(rgba(255,255,255,.022) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.022) 1px, transparent 1px);
  background-size: auto, auto, 40px 40px, 40px 40px;
  background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
}

::selection { background: rgba(0,212,255,.3); color: #fff; }

/* 自定义滚动条 */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: linear-gradient(var(--primary-dim), #163a5a);
  border-radius: 999px;
  border: 2px solid var(--bg);
}
::-webkit-scrollbar-thumb:hover { background: var(--primary); }

/* ---------- 顶部标题 ---------- */
.site-header {
  padding: 30px 34px 20px;
  border-bottom: 1px solid var(--border-soft);
  background:
    linear-gradient(180deg, rgba(10,16,40,.9), rgba(7,7,19,.2)),
    radial-gradient(600px 200px at 20% 0%, rgba(0,212,255,.10), transparent 70%);
  position: relative;
}
.site-header h1 {
  font-family: var(--font-title);
  font-size: 30px;
  margin: 0 0 6px;
  letter-spacing: 3px;
  color: #fff;
  text-shadow: 0 0 22px rgba(0,212,255,.5);
}
.site-header .sub {
  color: var(--text-dim);
  font-size: 14.5px;
  letter-spacing: .5px;
}
.breadcrumb {
  margin-top: 12px;
  font-size: 13px;
  color: var(--text-dim);
}
.breadcrumb a { color: var(--primary); text-decoration: none; transition: color .2s; }
.breadcrumb a:hover { color: #fff; text-shadow: var(--glow); }

/* ---------- 顶部导航 ---------- */
.topnav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding: 13px 34px;
  background: rgba(10,10,26,.7);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-soft);
  position: sticky;
  top: 0;
  z-index: 50;
}
.topnav a {
  text-decoration: none;
  color: var(--text-dim);
  padding: 8px 18px;
  border: 1px solid var(--border-soft);
  border-radius: 999px;
  font-size: 13.5px;
  letter-spacing: .5px;
  transition: all .22s ease;
  position: relative;
}
.topnav a::before {
  content: "";
  position: absolute; inset: 0;
  border-radius: 999px;
  background: linear-gradient(120deg, rgba(0,212,255,.0), rgba(0,212,255,.0));
  transition: all .22s;
}
.topnav a:hover {
  color: #fff;
  border-color: var(--primary);
  background: rgba(0,212,255,.10);
  box-shadow: 0 0 16px rgba(0,212,255,.25);
  transform: translateY(-1px);
}
.topnav a.active {
  color: #04121a;
  font-weight: 700;
  background: linear-gradient(120deg, var(--primary), #6ef0ff);
  border-color: transparent;
  box-shadow: var(--glow);
}

/* ---------- 布局 ---------- */
.layout {
  display: grid;
  grid-template-columns: 264px 1fr;
  gap: 26px;
  padding: 30px 34px 70px;
  max-width: 1320px;
  margin: 0 auto;
}
.sidebar {
  position: sticky;
  top: 82px;
  align-self: start;
  background: var(--panel);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 18px 16px;
  max-height: calc(100vh - 112px);
  overflow: auto;
  box-shadow: var(--shadow);
}
.sidebar h3 {
  font-family: var(--font-title);
  font-size: 12.5px;
  color: var(--accent);
  margin: 16px 6px 8px;
  letter-spacing: 1.5px;
  text-transform: uppercase;
}
.sidebar h3:first-child { margin-top: 2px; }
.sidebar a {
  display: block;
  color: var(--text-dim);
  text-decoration: none;
  padding: 7px 12px;
  border-radius: var(--radius-sm);
  font-size: 13.5px;
  border-left: 2px solid transparent;
  transition: all .18s;
}
.sidebar a:hover {
  color: var(--text);
  background: var(--panel-2);
  border-left-color: var(--accent);
  padding-left: 14px;
}
.sidebar a:target, .sidebar a.is-active {
  color: var(--primary);
  background: rgba(0,212,255,.08);
  border-left-color: var(--primary);
}

.content { min-width: 0; }

/* ---------- 卡片（玻璃拟态） ---------- */
.card {
  background: var(--panel);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 22px 24px;
  margin-bottom: 22px;
  box-shadow: var(--shadow);
  transition: transform .2s, border-color .2s, box-shadow .2s;
}
.card:hover {
  border-color: var(--border);
  box-shadow: 0 14px 40px rgba(0,0,0,.5), 0 0 26px rgba(0,212,255,.08);
}
.card h2 {
  font-family: var(--font-title);
  font-size: 19px;
  color: #fff;
  margin: 0 0 14px;
  letter-spacing: 1px;
  padding-left: 14px;
  border-left: 4px solid var(--primary);
  text-shadow: 0 0 16px rgba(0,212,255,.25);
}
.card h3 { color: var(--accent); font-size: 16.5px; margin: 20px 0 8px; }
.card h4 { color: var(--success); font-size: 14.5px; margin: 14px 0 6px; letter-spacing: .5px; }

/* ---------- 网格与模块卡片 ---------- */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 16px;
}
.module-card {
  display: block;
  text-decoration: none;
  background: linear-gradient(160deg, rgba(38,38,74,.6), rgba(18,18,42,.55));
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 18px 20px;
  transition: transform .2s, border-color .2s, box-shadow .2s;
  color: var(--text);
  position: relative;
  overflow: hidden;
}
.module-card::after {
  content: "";
  position: absolute; right: -30px; top: -30px;
  width: 90px; height: 90px; border-radius: 50%;
  background: radial-gradient(circle, rgba(0,212,255,.18), transparent 70%);
  opacity: 0; transition: opacity .25s;
}
.module-card:hover {
  transform: translateY(-4px);
  border-color: var(--primary);
  box-shadow: 0 16px 38px rgba(0,0,0,.5), 0 0 24px rgba(0,212,255,.2);
}
.module-card:hover::after { opacity: 1; }
.module-card .tag {
  display: inline-block;
  font-size: 11px;
  color: #04121a;
  background: linear-gradient(120deg, var(--primary), #6ef0ff);
  padding: 3px 11px;
  border-radius: 999px;
  margin-bottom: 10px;
  font-weight: 700;
  letter-spacing: .5px;
}
.module-card h3 { color: #fff; margin: 4px 0 7px; font-size: 17.5px; font-family: var(--font-title); letter-spacing: .5px; }
.module-card p { color: var(--text-dim); font-size: 13px; margin: 0; line-height: 1.6; }

/* ---------- 文本 ---------- */
.content p { margin: 11px 0; color: #d6d9ec; }
.content ul, .content ol { padding-left: 24px; }
.content li { margin: 7px 0; }
.content li::marker { color: var(--primary); }
.content a { color: var(--primary); text-decoration: none; border-bottom: 1px dashed rgba(0,212,255,.4); transition: all .2s; }
.content a:hover { color: #fff; border-bottom-color: #fff; }
.content strong { color: var(--warning); font-weight: 600; }
.content code {
  background: rgba(0,0,0,.35);
  border: 1px solid var(--border-soft);
  padding: 2px 7px;
  border-radius: 6px;
  font-size: 13px;
  font-family: var(--font-mono);
  color: var(--success);
}

/* ---------- 公式块（KaTeX 渲染） ---------- */
.formula {
  background: linear-gradient(160deg, rgba(8,10,28,.9), rgba(14,16,40,.8));
  border: 1px solid var(--border-soft);
  border-left: 4px solid var(--primary);
  border-radius: 10px;
  padding: 14px 18px;
  margin: 16px 0;
  overflow-x: auto;
  font-size: 15.5px;
  text-align: center;
  box-shadow: inset 0 0 24px rgba(0,212,255,.05);
}
.formula .label {
  color: var(--text-dim);
  font-size: 12px;
  display: block;
  margin-bottom: 6px;
  text-align: left;
  letter-spacing: 1px;
}
.formula .katex { font-size: 1.18em; color: #eaf6ff; }
.formula .katex-display { margin: 4px 0; }

/* ---------- 例题 ---------- */
.example {
  background: linear-gradient(160deg, rgba(255,107,157,.07), rgba(255,107,157,.02));
  border: 1px solid rgba(255,107,157,.32);
  border-left: 4px solid var(--accent);
  border-radius: 10px;
  padding: 15px 20px;
  margin: 16px 0;
}
.example .ex-title {
  color: var(--accent);
  font-weight: 700;
  font-size: 13px;
  letter-spacing: 1.5px;
  margin-bottom: 8px;
  display: flex; align-items: center; gap: 8px;
}
.example .ex-title::before { content: "✎"; font-size: 15px; }
.example .sol { color: #d6d9ec; font-size: 14.5px; }
.example .sol strong { color: var(--success); }

/* ---------- 提示框 ---------- */
.note {
  border-left: 4px solid var(--warning);
  background: rgba(255,180,84,.07);
  padding: 12px 18px;
  margin: 16px 0;
  border-radius: 0 10px 10px 0;
  font-size: 14.5px;
  color: #ecd9b8;
}
.note::before { content: "💡 "; }

/* ---------- 表格 ---------- */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
  font-size: 13.5px;
  overflow: hidden;
  border-radius: 10px;
}
th, td {
  border: 1px solid var(--border-soft);
  padding: 10px 13px;
  text-align: left;
}
th {
  background: linear-gradient(120deg, rgba(0,212,255,.16), rgba(0,212,255,.06));
  color: var(--primary);
  font-weight: 600;
  letter-spacing: .5px;
}
tr:nth-child(even) td { background: rgba(255,255,255,.025); }
tbody tr { transition: background .15s; }
tbody tr:hover td { background: rgba(0,212,255,.06); }

/* ---------- 徽章 ---------- */
.badge {
  display: inline-block;
  font-size: 11px;
  padding: 2px 9px;
  border-radius: 6px;
  margin-right: 6px;
  letter-spacing: .5px;
}
.badge.core { background: rgba(0,255,136,.14); color: var(--success); border: 1px solid rgba(0,255,136,.4); }
.badge.adv  { background: rgba(255,180,84,.14); color: var(--warning); border: 1px solid rgba(255,180,84,.4); }

/* ---------- 进度条 ---------- */
.progress {
  height: 9px;
  background: rgba(255,255,255,.06);
  border-radius: 999px;
  overflow: hidden;
  margin: 10px 0 4px;
}
.progress > span {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--success));
  box-shadow: 0 0 12px rgba(0,212,255,.5);
}

/* ---------- 页脚 ---------- */
.site-footer {
  border-top: 1px solid var(--border-soft);
  padding: 22px 34px;
  color: var(--text-dim);
  font-size: 12.5px;
  text-align: center;
  letter-spacing: .5px;
}

/* ---------- 交互式动态示意图（canvas） ---------- */
.sim {
  background: linear-gradient(160deg, rgba(8,10,28,.9), rgba(14,16,40,.8));
  border: 1px solid var(--border-soft);
  border-left: 4px solid var(--accent);
  border-radius: 10px;
  padding: 14px 16px;
  margin: 18px 0;
}
.sim-canvas {
  display: block;
  width: 100%;
  height: auto;
  background: #05050f;
  border: 1px solid var(--border-soft);
  border-radius: 8px;
}
.sim-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  margin-top: 12px;
  font-size: 13px;
  color: var(--text-dim);
}
.sim-controls label { display: inline-flex; align-items: center; gap: 8px; }
.sim-controls input[type="range"] {
  -webkit-appearance: none; appearance: none;
  width: 150px; height: 4px; border-radius: 999px;
  background: linear-gradient(90deg, var(--primary-dim), rgba(255,255,255,.15));
  outline: none;
}
.sim-controls input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none; appearance: none;
  width: 15px; height: 15px; border-radius: 50%;
  background: linear-gradient(120deg, var(--primary), #6ef0ff);
  box-shadow: var(--glow); cursor: pointer; border: none;
}
.sim-controls input[type="range"]::-moz-range-thumb {
  width: 15px; height: 15px; border-radius: 50%; border: none;
  background: linear-gradient(120deg, var(--primary), #6ef0ff); cursor: pointer;
}
.sim-btn {
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: #04121a;
  background: linear-gradient(120deg, var(--primary), #6ef0ff);
  border: none;
  border-radius: 999px;
  padding: 6px 16px;
  cursor: pointer;
  font-weight: 700;
  letter-spacing: .5px;
  transition: box-shadow .2s, transform .2s;
}
.sim-btn:hover { box-shadow: var(--glow); transform: translateY(-1px); }

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; padding: 22px 18px 60px; }
  .sidebar { position: static; max-height: none; }
  .site-header, .topnav { padding-left: 18px; padding-right: 18px; }
  .site-header h1 { font-size: 24px; }
}