/* ==========================================================================
   博王CN · 简体中文指南站 — 共享样式 /assets/site.css
   视觉语言：夜间导航仪 · 框架式导航 · 精密网格 · 锐利直角
   ========================================================================== */

/* ---------- 1. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body,
h1, h2, h3, h4, h5, h6,
p, figure, blockquote, dl, dd, ul, ol {
  margin: 0;
}

ul, ol {
  list-style: none;
  padding: 0;
}

img, svg, video {
  display: block;
  max-width: 100%;
}

a {
  color: inherit;
  text-decoration: none;
}

button, input, select, textarea {
  font: inherit;
  color: inherit;
}

button {
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

[hidden],
.is-hidden { display: none !important; }

/* ---------- 2. 设计变量 ---------- */
:root {
  /* 色彩系统 */
  --ink: #1B2A4A;
  --abyss: #0E1830;
  --amber: #FF8A3D;
  --amber-soft: #FFB27A;
  --mist: #8FA3BF;
  --paper: #F5F1E8;
  --jade: #3E8E7E;
  --jade-soft: #7FC3B4;
  --steel: #2C3E5C;
  --ash: #D9D2C3;
  --alert: #D9694C;

  /* 框架与节奏 */
  --rail: 248px;
  --header-h: 64px;
  --u: 8px;

  --line: rgba(143, 163, 191, 0.20);
  --line-strong: rgba(143, 163, 191, 0.42);

  /* 字体 */
  --font-sans: "Source Han Sans SC", "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

/* ---------- 3. 基础排版 ---------- */
html { background: var(--ink); }

body {
  min-height: 100vh;
  padding-left: var(--rail);
  background: var(--ink);
  color: var(--paper);
  font-family: var(--font-sans);
  font-size: 16px;
  font-weight: 400;
  line-height: 1.7;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -0.01em;
}

p { max-width: 42em; }

strong { font-weight: 700; }

:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 3px;
  border-radius: 0;
}

/* ---------- 4. 通用工具类 ---------- */
.wrap {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: calc(var(--u) * 9) clamp(20px, 4vw, 56px);
}

.wrap--tight {
  padding-top: calc(var(--u) * 5);
  padding-bottom: calc(var(--u) * 5);
}

.mono {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
}

.display {
  font-size: clamp(44px, 7.2vw, 104px);
  font-weight: 300;
  line-height: 1.02;
  letter-spacing: -0.03em;
}

.lede {
  max-width: 40em;
  font-size: 18px;
  line-height: 1.7;
  font-weight: 400;
  color: var(--paper);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.16em;
  color: var(--amber);
  text-transform: uppercase;
}

.eyebrow::before {
  content: "";
  width: 6px;
  height: 6px;
  background: var(--amber);
  flex: 0 0 auto;
}

.rule {
  height: 1px;
  margin: calc(var(--u) * 4) 0;
  border: 0;
  background: var(--line);
}

/* ---------- 5. 框架头部 ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--rail);
  display: flex;
  flex-direction: column;
  padding: calc(var(--u) * 3) calc(var(--u) * 2.5) calc(var(--u) * 3);
  background: var(--abyss);
  border-right: 1px solid var(--line-strong);
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: thin;
  z-index: 80;
}

/* skip link */
.skip-link {
  position: absolute;
  top: 8px;
  left: 12px;
  z-index: 200;
  padding: 10px 16px;
  background: var(--amber);
  color: var(--abyss);
  font-size: 13px;
  font-weight: 700;
  line-height: 1.4;
  transform: translateY(-200%);
  transition: transform 0.16s var(--ease);
}

.skip-link:focus {
  position: fixed;
  top: 12px;
  left: 12px;
  transform: none;
}

/* 品牌 */
.brand {
  display: block;
  padding-bottom: calc(var(--u) * 2);
  border-bottom: 1px solid var(--line);
}

.brand__mark {
  display: block;
  font-size: 25px;
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--paper);
  transition: color 0.18s var(--ease);
}

.brand:hover .brand__mark { color: var(--amber); }

.brand__sub {
  display: block;
  margin-top: 6px;
  font-family: var(--font-mono);
  font-size: 11px;
  line-height: 1.4;
  letter-spacing: 0.12em;
  color: var(--mist);
}

/* 常驻检索指南直达 */
.rail-guide {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-top: calc(var(--u) * 2.5);
  padding: 9px 11px;
  font-size: 13px;
  font-weight: 500;
  line-height: 1.4;
  color: var(--paper);
  background: rgba(255, 138, 61, 0.14);
  border: 1px solid rgba(255, 138, 61, 0.42);
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.rail-guide::after {
  content: "→";
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1;
  color: var(--amber);
}

.rail-guide:hover {
  background: var(--amber);
  border-color: var(--amber);
  color: var(--abyss);
}

.rail-guide:hover::after { color: var(--abyss); }

/* 移动菜单按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border: 1px solid var(--line-strong);
  color: var(--paper);
  font-size: 13px;
  font-weight: 500;
  line-height: 1.4;
  transition: border-color 0.18s var(--ease), color 0.18s var(--ease);
}

.nav-toggle:hover {
  border-color: var(--amber);
  color: var(--amber);
}

.nav-toggle__bars {
  display: flex;
  flex-direction: column;
  gap: 3px;
  width: 16px;
  flex: 0 0 auto;
}

.nav-toggle__bar {
  display: block;
  width: 100%;
  height: 2px;
  background: currentColor;
  transition: transform 0.18s var(--ease), opacity 0.18s var(--ease);
}

.nav-toggle__label { white-space: nowrap; }

.site-header[data-open="true"] .nav-toggle {
  border-color: var(--amber);
  color: var(--amber);
}

.site-header[data-open="true"] .nav-toggle__bar:nth-child(1) {
  transform: translateY(5px) rotate(45deg);
}

.site-header[data-open="true"] .nav-toggle__bar:nth-child(2) {
  opacity: 0;
}

.site-header[data-open="true"] .nav-toggle__bar:nth-child(3) {
  transform: translateY(-5px) rotate(-45deg);
}

/* 主导航 */
.frame-nav { margin-top: calc(var(--u) * 3); }

.frame-nav__list {
  display: flex;
  flex-direction: column;
}

.frame-nav__item {
  border-top: 1px solid var(--line);
}

.frame-nav__item:last-child {
  border-bottom: 1px solid var(--line);
}

.frame-nav__link {
  position: relative;
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 11px 4px 11px 10px;
  font-size: 15px;
  font-weight: 500;
  line-height: 1.4;
  color: var(--mist);
  transition: color 0.18s var(--ease), background-color 0.18s var(--ease);
}

.frame-nav__link::before {
  content: "";
  position: absolute;
  top: 8px;
  bottom: 8px;
  left: 0;
  width: 2px;
  background: transparent;
  transition: background-color 0.18s var(--ease);
}

.frame-nav__link:hover {
  color: var(--paper);
  background: rgba(143, 163, 191, 0.08);
}

.frame-nav__link:hover::before { background: var(--mist); }

.frame-nav__link[aria-current="page"] {
  color: var(--amber);
  background: rgba(255, 138, 61, 0.10);
}

.frame-nav__link[aria-current="page"]::before { background: var(--amber); }

.frame-nav__index {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--mist);
  transition: color 0.18s var(--ease);
}

.frame-nav__link[aria-current="page"] .frame-nav__index { color: var(--amber-soft); }

/* 版本与行动 */
.frame-tools {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-top: auto;
  padding-top: calc(var(--u) * 3.5);
}

.frame-tools__version {
  display: flex;
  align-items: center;
  gap: 7px;
  max-width: none;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--mist);
}

.frame-tools__dot {
  width: 6px;
  height: 6px;
  flex: 0 0 auto;
  background: var(--jade);
}

.frame-tools__cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 0 14px;
  font-size: 14px;
  font-weight: 700;
  line-height: 1.3;
  color: var(--abyss);
  background: var(--amber);
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease);
}

.frame-tools__cta:hover {
  background: var(--amber-soft);
}

/* 阅读进度条 */
.scroll-meter {
  position: fixed;
  top: 0;
  left: calc(var(--rail) - 2px);
  width: 2px;
  height: calc(var(--progress, 0) * 100%);
  background: var(--amber);
  z-index: 90;
  pointer-events: none;
}

/* ---------- 6. 框架页脚 ---------- */
.site-footer {
  margin-top: calc(var(--u) * 12);
  background: var(--abyss);
  border-top: 1px solid var(--line-strong);
  color: var(--mist);
  font-size: 14px;
}

.footer-top {
  display: grid;
  grid-template-columns: minmax(180px, 1fr) minmax(0, 2.2fr);
  gap: 40px;
  padding: calc(var(--u) * 7) clamp(20px, 4vw, 64px) 0;
}

.footer-brand__mark {
  display: inline-block;
  font-size: 24px;
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--paper);
  transition: color 0.18s var(--ease);
}

.footer-brand__mark:hover { color: var(--amber); }

.footer-brand__note {
  margin-top: 10px;
  max-width: 24em;
  font-size: 13px;
  line-height: 1.7;
  color: var(--mist);
}

.footer-nav {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 32px;
}

.footer-col__title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.16em;
  color: var(--amber);
}

.footer-col__list li + li { margin-top: 9px; }

.footer-link {
  display: inline-block;
  padding: 2px 0;
  font-size: 14px;
  line-height: 1.6;
  color: var(--paper);
  transition: color 0.18s var(--ease), transform 0.18s var(--ease);
}

.footer-link:hover {
  color: var(--amber);
  transform: translateX(2px);
}

.footer-contact {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 14px 32px;
  margin: calc(var(--u) * 5) clamp(20px, 4vw, 64px) 0;
  padding-top: calc(var(--u) * 3);
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.03em;
}

.footer-contact__item {
  display: flex;
  align-items: baseline;
  gap: 10px;
  max-width: none;
  line-height: 1.9;
}

.footer-contact__key {
  flex: 0 0 auto;
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--amber-soft);
}

.footer-base {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px 32px;
  margin-top: calc(var(--u) * 5);
  padding: calc(var(--u) * 2.5) clamp(20px, 4vw, 64px) calc(var(--u) * 3.5);
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.04em;
  color: var(--mist);
}

.footer-base__meta {
  max-width: none;
  line-height: 1.7;
}

/* ---------- 7. 基础组件 ---------- */
/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 44px;
  padding: 0 20px;
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: 0.01em;
  border: 1px solid transparent;
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.btn--primary {
  background: var(--amber);
  border-color: var(--amber);
  color: var(--abyss);
}

.btn--primary:hover {
  background: var(--amber-soft);
  border-color: var(--amber-soft);
}

.btn--ghost {
  background: transparent;
  border-color: var(--line-strong);
  color: var(--paper);
}

.btn--ghost:hover {
  border-color: var(--amber);
  color: var(--amber);
}

/* 面包屑 */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--mist);
}

.breadcrumb a {
  color: var(--mist);
  transition: color 0.18s var(--ease);
}

.breadcrumb a:hover { color: var(--amber); }

.breadcrumb__sep {
  color: var(--steel);
  user-select: none;
}

.breadcrumb [aria-current="page"] { color: var(--paper); }

/* 模块标题行 */
.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px 24px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--line-strong);
}

.section-head__title {
  font-size: 28px;
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -0.01em;
}

.section-head__meta {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--mist);
}

/* 面板 */
.panel {
  padding: calc(var(--u) * 3);
  background: linear-gradient(180deg, rgba(44, 62, 92, 0.55), rgba(27, 42, 74, 0.55));
  border: 1px solid var(--line);
}

/* 标签 */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 9px;
  font-family: var(--font-mono);
  font-size: 11px;
  line-height: 1.6;
  letter-spacing: 0.08em;
  color: var(--mist);
  background: rgba(143, 163, 191, 0.12);
  border: 1px solid var(--line);
}

.tag--amber {
  color: var(--amber);
  background: rgba(255, 138, 61, 0.12);
  border-color: rgba(255, 138, 61, 0.45);
}

.tag--jade {
  color: var(--jade-soft);
  background: rgba(62, 142, 126, 0.18);
  border-color: rgba(62, 142, 126, 0.55);
}

/* 图片 / 示意图容器 */
.media-frame {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  border: 1px solid var(--line-strong);
  background-color: var(--steel);
  background-image:
    repeating-linear-gradient(0deg, rgba(143, 163, 191, 0.16) 0 1px, transparent 1px 32px),
    repeating-linear-gradient(90deg, rgba(143, 163, 191, 0.16) 0 1px, transparent 1px 32px);
}

.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--tall { aspect-ratio: 3 / 4; }

.media-frame > img,
.media-frame > svg {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media-frame__caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.05em;
  line-height: 1.7;
  color: var(--mist);
}

/* ---------- 8. 响应式：平板与手机 ---------- */
@media (max-width: 1023px) {
  body { padding-left: 0; }

  .site-header {
    position: sticky;
    top: 0;
    left: auto;
    right: auto;
    bottom: auto;
    width: 100%;
    flex-direction: row;
    flex-wrap: wrap;
    align-items: center;
    gap: 0;
    padding: 0 16px;
    border-right: 0;
    border-bottom: 1px solid var(--line-strong);
    overflow: visible;
  }

  .brand {
    order: 1;
    flex: 0 1 auto;
    padding: 14px 0;
    border-bottom: 0;
  }

  .brand__mark { font-size: 18px; letter-spacing: -0.01em; }
  .brand__sub { display: none; }

  .rail-guide {
    order: 2;
    margin: 0;
    padding: 6px 9px;
    font-size: 12px;
    background: rgba(255, 138, 61, 0.16);
  }

  .rail-guide::after { display: none; }

  .nav-toggle {
    order: 3;
    display: inline-flex;
    margin-left: auto;
  }

  .frame-nav {
    order: 4;
    display: none;
    width: 100%;
    margin: 0;
    padding: 8px 0;
    border-top: 1px solid var(--line);
  }

  .site-header[data-open="true"] .frame-nav { display: block; }

  .frame-nav__link {
    padding: 12px 4px 12px 12px;
    font-size: 15px;
  }

  .frame-tools {
    order: 5;
    display: none;
    width: 100%;
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin-top: 0;
    padding: 12px 0 16px;
    border-top: 1px solid var(--line);
  }

  .site-header[data-open="true"] .frame-tools { display: flex; }

  .frame-tools__version { font-size: 11px; }
  .frame-tools__cta { min-height: 38px; padding: 0 14px; font-size: 13px; }

  .scroll-meter {
    position: fixed;
    top: auto;
    bottom: 0;
    left: 0;
    right: 0;
    width: calc(var(--progress, 0) * 100%);
    height: 2px;
  }

  .footer-top {
    grid-template-columns: 1fr;
    gap: 32px;
    padding-top: calc(var(--u) * 5);
  }

  .footer-nav { gap: 24px; }
}

@media (max-width: 900px) {
  .footer-nav { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 640px) {
  .wrap { padding-top: calc(var(--u) * 6); padding-bottom: calc(var(--u) * 6); }

  .display { font-size: clamp(38px, 11vw, 60px); }

  .lede { font-size: 16px; }

  .section-head__title { font-size: 22px; }

  .footer-nav { grid-template-columns: 1fr; gap: 28px; }

  .footer-base { flex-direction: column; align-items: flex-start; }

  .panel { padding: calc(var(--u) * 2); }
}

/* ---------- 9. 可访问性：减弱动效 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    transition-delay: 0ms !important;
  }

  .skip-link { transition: none; }
  .footer-link:hover { transform: none; }
}