/* ============================================================
   fq-compressor — FQC v2 文档站样式
   深色科技风，零外部依赖
   ============================================================ */

:root {
  --bg: #0a1120;
  --bg-elev: #0e1728;
  --bg-card: #101a2e;
  --bg-code: #060b14;
  --border: #1c2a45;
  --border-soft: #16223a;
  --text: #dbe6f7;
  --text-muted: #8fa0c0;
  --text-faint: #5f7194;

  --cyan: #38bdf8;      /* 格式 */
  --green: #34d399;     /* 算法 */
  --amber: #fbbf24;     /* 架构 */
  --pink: #f472b6;
  --red: #fb7185;
  --violet: #a78bfa;

  --mono: ui-monospace, "SF Mono", "Cascadia Code", "JetBrains Mono",
          "Fira Code", Consolas, "Liberation Mono", monospace;
  --sans: -apple-system, "Segoe UI", "PingFang SC", "Hiragino Sans GB",
          "Microsoft YaHei", "Noto Sans CJK SC", "Helvetica Neue", Arial, sans-serif;

  --sidebar-w: 264px;
  --content-w: 860px;
  --radius: 10px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(1200px 600px at 80% -10%, rgba(56, 189, 248, 0.06), transparent 60%),
    radial-gradient(900px 500px at -10% 20%, rgba(52, 211, 153, 0.05), transparent 55%),
    var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

/* ---------- 布局骨架 ---------- */

.layout {
  display: grid;
  grid-template-columns: var(--sidebar-w) minmax(0, 1fr);
  max-width: 1280px;
  margin: 0 auto;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  padding: 28px 18px 40px 24px;
  border-right: 1px solid var(--border-soft);
  background: rgba(10, 17, 32, 0.85);
  backdrop-filter: blur(6px);
  scrollbar-width: thin;
}

.main {
  min-width: 0;
  padding: 0 48px 96px;
}

.content { max-width: var(--content-w); }

/* ---------- 侧栏 ---------- */

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 6px 10px 22px;
}

.brand .logo {
  width: 34px;
  height: 34px;
  flex: none;
}

.brand .logo svg { display: block; }

.brand-name { font-weight: 700; font-size: 17px; letter-spacing: 0.2px; }

.brand-sub {
  font-size: 11.5px;
  color: var(--text-faint);
  font-family: var(--mono);
  margin-top: 1px;
}

.nav-group-label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--text-faint);
  padding: 18px 10px 6px;
  font-weight: 600;
}

.nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav a {
  display: block;
  padding: 6px 10px;
  margin: 1px 0;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 13.5px;
  border-left: 2px solid transparent;
  border-radius: 4px;
  transition: color 0.15s, background 0.15s;
}

.nav a:hover { color: var(--text); background: rgba(56, 189, 248, 0.06); }

.nav a.active {
  color: #fff;
  border-left-color: var(--cyan);
  background: linear-gradient(90deg, rgba(56, 189, 248, 0.14), transparent);
}

.nav .sub a { padding-left: 26px; font-size: 12.8px; }

.nav .sub a.active { border-left-color: var(--green); }

.nav .sub a.cat-format.active { border-left-color: var(--cyan); }
.nav .sub a.cat-algorithm.active { border-left-color: var(--green); }
.nav .sub a.cat-architecture.active { border-left-color: var(--amber); }

/* 汉堡菜单（移动端） */
.nav-toggle {
  display: none;
  position: sticky;
  top: 0;
  z-index: 40;
  width: 100%;
  padding: 12px 20px;
  background: rgba(10, 17, 32, 0.95);
  border-bottom: 1px solid var(--border-soft);
  border-top: none; border-left: none; border-right: none;
  color: var(--text);
  font-family: var(--sans);
  font-size: 15px;
  font-weight: 600;
  text-align: left;
  cursor: pointer;
}

.nav-toggle .hamburger {
  display: inline-block;
  width: 18px; height: 14px;
  margin-right: 10px;
  position: relative;
  vertical-align: -2px;
}
.nav-toggle .hamburger span {
  position: absolute; left: 0; width: 18px; height: 2px;
  background: var(--text); border-radius: 2px; transition: 0.25s;
}
.nav-toggle .hamburger span:nth-child(1) { top: 0; }
.nav-toggle .hamburger span:nth-child(2) { top: 6px; }
.nav-toggle .hamburger span:nth-child(3) { top: 12px; }
.nav-toggle.open .hamburger span:nth-child(1) { top: 6px; transform: rotate(45deg); }
.nav-toggle.open .hamburger span:nth-child(2) { opacity: 0; }
.nav-toggle.open .hamburger span:nth-child(3) { top: 6px; transform: rotate(-45deg); }

/* ---------- Hero ---------- */

.hero {
  padding: 56px 0 40px;
  border-bottom: 1px solid var(--border-soft);
  margin-bottom: 44px;
}

.hero h1 {
  font-size: 34px;
  line-height: 1.2;
  margin: 0 0 8px;
  letter-spacing: -0.5px;
}

.hero h1 .fqc {
  background: linear-gradient(90deg, var(--cyan), var(--green));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero .tagline {
  font-size: 17px;
  color: var(--text-muted);
  margin: 0 0 20px;
  max-width: 620px;
}

.hero .badges {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 22px;
}

.badge {
  font-family: var(--mono);
  font-size: 12px;
  padding: 3px 10px;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--text-muted);
  background: var(--bg-elev);
}

.badge.accent-cyan { color: var(--cyan); border-color: rgba(56,189,248,0.35); }
.badge.accent-green { color: var(--green); border-color: rgba(52,211,153,0.35); }
.badge.accent-amber { color: var(--amber); border-color: rgba(251,191,36,0.35); }

.stat-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 14px;
  margin-top: 26px;
}

.stat {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 14px 16px;
}

.stat .num {
  font-family: var(--mono);
  font-size: 26px;
  font-weight: 700;
  color: var(--cyan);
  line-height: 1.1;
}

.stat .lbl { font-size: 12.5px; color: var(--text-muted); margin-top: 4px; }

/* ---------- 章节 ---------- */

section.section {
  margin-top: 56px;
  scroll-margin-top: 24px;
}

.section-head {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 8px;
}

.section-num {
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 6px;
  letter-spacing: 0.5px;
}

.cat-format .section-num { background: rgba(56,189,248,0.14); color: var(--cyan); }
.cat-algorithm .section-num { background: rgba(52,211,153,0.14); color: var(--green); }
.cat-architecture .section-num { background: rgba(251,191,36,0.14); color: var(--amber); }

.section-head h2 {
  margin: 0;
  font-size: 26px;
  letter-spacing: -0.3px;
}

.section-lead { color: var(--text-muted); margin: 8px 0 26px; max-width: 700px; }

h3 {
  font-size: 19px;
  margin: 38px 0 12px;
  padding-top: 8px;
  letter-spacing: -0.2px;
}

h3 .kicker {
  font-size: 12px;
  color: var(--text-faint);
  font-family: var(--mono);
  display: block;
  margin-bottom: 2px;
  text-transform: uppercase;
  letter-spacing: 1px;
}

h4 { font-size: 16px; margin: 26px 0 10px; }

p { margin: 12px 0; }

strong { color: #eaf2ff; }

a { color: var(--cyan); text-decoration: none; }
a:hover { text-decoration: underline; }

/* 信息卡 */

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 18px 20px;
  margin: 18px 0;
}

.card.tip { border-left: 3px solid var(--green); }
.card.warn { border-left: 3px solid var(--amber); }
.card.danger { border-left: 3px solid var(--red); }

.card .card-title {
  font-weight: 700;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.card .card-title .tag {
  font-size: 11px;
  font-family: var(--mono);
  padding: 1px 8px;
  border-radius: 999px;
}
.card.tip .tag { background: rgba(52,211,153,0.16); color: var(--green); }
.card.warn .tag { background: rgba(251,191,36,0.16); color: var(--amber); }
.card.danger .tag { background: rgba(251,113,133,0.16); color: var(--red); }

.card p:last-child { margin-bottom: 0; }

/* 代码块与行内码 */

pre {
  background: var(--bg-code);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 16px 18px;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.65;
  color: #c9d9f0;
  margin: 16px 0;
}

pre code { background: none; padding: 0; color: inherit; }

code {
  font-family: var(--mono);
  font-size: 0.86em;
  background: rgba(56, 189, 248, 0.08);
  border: 1px solid rgba(56, 189, 248, 0.14);
  border-radius: 4px;
  padding: 1px 6px;
  color: #bfe3ff;
}

pre code .c { color: #5f7194; }       /* 注释 */
pre code .k { color: var(--violet); } /* 关键字/强调 */
pre code .hl { color: var(--amber); } /* 高亮 */

/* 表格 */

.table-wrap { overflow-x: auto; margin: 16px 0; }

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

th, td {
  text-align: left;
  padding: 9px 14px;
  border-bottom: 1px solid var(--border-soft);
  vertical-align: top;
}

th {
  font-size: 12.5px;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--text-muted);
  background: rgba(255,255,255,0.02);
  white-space: nowrap;
}

tbody tr:hover { background: rgba(56,189,248,0.03); }

td.num, th.num { text-align: right; font-family: var(--mono); }

/* 图表容器 */

.figure {
  margin: 22px 0;
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  background: var(--bg-elev);
  padding: 8px;
}

.figure img, .figure svg {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 6px;
}

.figcaption {
  font-size: 12.5px;
  color: var(--text-faint);
  text-align: center;
  padding: 10px 8px 6px;
  font-family: var(--mono);
}

/* 列表 */

ul, ol { padding-left: 22px; }
li { margin: 5px 0; }

/* 步骤流程 */

.steps { counter-reset: step; margin: 18px 0; padding: 0; list-style: none; }

.steps li {
  position: relative;
  padding: 12px 14px 12px 46px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  margin: 10px 0;
}

.steps li::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: 12px; top: 14px;
  width: 24px; height: 24px;
  border-radius: 50%;
  background: rgba(56,189,248,0.15);
  color: var(--cyan);
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* 键值对网格 */

.kv-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 12px;
  margin: 16px 0;
}

.kv {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 12px 14px;
}

.kv .k { font-family: var(--mono); font-size: 12px; color: var(--text-faint); }
.kv .v { margin-top: 4px; font-size: 14px; }

/* ---------- 页脚 ---------- */

.site-footer {
  margin-top: 72px;
  padding-top: 26px;
  border-top: 1px solid var(--border-soft);
  color: var(--text-faint);
  font-size: 13px;
}

.site-footer .links { margin-bottom: 8px; }
.site-footer .links a { margin-right: 18px; }

/* ---------- 响应式 ---------- */

@media (max-width: 980px) {
  .nav-toggle { display: block; }

  .layout { display: block; }

  .sidebar {
    position: fixed;
    top: 0; left: 0; bottom: 0;
    width: min(300px, 82vw);
    transform: translateX(-100%);
    transition: transform 0.25s ease;
    z-index: 50;
    background: rgba(9, 14, 27, 0.98);
    border-right: 1px solid var(--border);
  }

  .sidebar.open { transform: translateX(0); }

  .sidebar-backdrop {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    z-index: 45;
  }
  .sidebar-backdrop.show { display: block; }

  .main { padding: 0 20px 80px; }
  .hero { padding: 36px 0 28px; }
  .hero h1 { font-size: 27px; }
  .section-head h2 { font-size: 22px; }
}

@media (max-width: 560px) {
  .stat-row { grid-template-columns: 1fr 1fr; }
  .stat .num { font-size: 21px; }
  .hero .badges { gap: 6px; }
}

/* 打印 */
@media print {
  .sidebar, .nav-toggle { display: none; }
  .layout { display: block; }
  .main { padding: 0; }
  body { background: #fff; color: #000; }
  a { color: inherit; }
}