/* ==========================================================================
   永乐高指南 · 共享样式表  /assets/site.css
   1 重置  2 设计变量  3 中文排版  4 页面骨架与框架线  5 头部
   6 页脚  7 通用组件  8 媒体与设备容器  9 动效  10 响应式与无障碍
   ========================================================================== */

/* ---------- 1. 重置 ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
img, svg, video { display: block; max-width: 100%; }
button { font: inherit; color: inherit; background: none; border: 0; }
table { border-collapse: collapse; width: 100%; }
[hidden] { display: none !important; }

/* ---------- 2. 设计变量 ---------- */
:root {
  --c-ink: #050B18;
  --c-navy: #0B1B33;
  --c-steel: #123A5E;
  --c-cyan: #00E5D0;
  --c-cyan-soft: #7CF3E6;
  --c-orange: #FF7A3D;
  --c-paper: #F4F7FA;
  --c-mist: #A7B6C8;
  --c-amber: #FFC24B;

  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", "Noto Sans SC", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-serif: "Source Han Serif SC", "Noto Serif SC", "Songti SC", Georgia, "Times New Roman", serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", "Courier New", monospace;

  --maxw: 1440px;
  --gutter: clamp(18px, 4vw, 56px);
  --line-frame: 1px solid rgba(0, 229, 208, 0.20);
  --line-soft: 1px solid rgba(167, 182, 200, 0.14);
  --ease-out: cubic-bezier(0.2, 0.7, 0.3, 1);
  --shadow-panel: 0 24px 48px rgba(0, 0, 0, 0.38);

  --fz-56: clamp(34px, 5.2vw, 56px);
  --fz-38: clamp(26px, 3.4vw, 38px);
  --fz-26: clamp(20px, 2.4vw, 26px);
  --fz-19: clamp(17px, 1.6vw, 19px);
  --fz-16: clamp(15px, 1.1vw, 16.5px);
}

/* ---------- 3. 中文排版与页面底色 ---------- */
body {
  margin: 0;
  min-height: 100%;
  font-family: var(--font-sans);
  font-size: var(--fz-16);
  font-weight: 400;
  line-height: 1.85;
  letter-spacing: 0.01em;
  color: #D9E3EE;
  background-color: var(--c-ink);
  /* 框架式导航：左右两条固定竖线，成为页面的视觉边框 */
  background-image:
    linear-gradient(90deg, rgba(0, 229, 208, 0.12) 0 1px, transparent 1px),
    linear-gradient(270deg, rgba(0, 229, 208, 0.12) 0 1px, transparent 1px);
  background-repeat: no-repeat, no-repeat;
  background-position: left 20px top, right 20px top;
  background-size: 1px 100%, 1px 100%;
  background-attachment: fixed, fixed;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
/* 深海墨底上的极低透明度颗粒 */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 90;
  pointer-events: none;
  opacity: 0.04;
  background-image: radial-gradient(rgba(244, 247, 250, 0.8) 0.5px, transparent 0.6px);
  background-size: 4px 4px;
}

h1, h2, h3, h4 { margin: 0 0 0.5em; color: var(--c-paper); font-weight: 800; letter-spacing: -0.02em; line-height: 1.05; }
h1 { font-size: var(--fz-56); }
h2 { font-size: var(--fz-38); }
h3 { font-size: var(--fz-26); line-height: 1.25; }
h4 { font-size: var(--fz-19); line-height: 1.4; }
p { margin: 0 0 1.15em; }
p:last-child { margin-bottom: 0; }
ul, ol { margin: 0 0 1.15em; padding-left: 1.2em; }
li { margin-bottom: 0.35em; }
a { color: var(--c-cyan-soft); text-decoration: none; transition: color 0.2s var(--ease-out); }
a:hover { color: var(--c-cyan); }
strong, b { color: var(--c-paper); font-weight: 700; }
hr { border: 0; height: 1px; background: rgba(167, 182, 200, 0.18); margin: clamp(28px, 4vw, 56px) 0; }
code, kbd, samp { font-family: var(--font-mono); font-size: 0.92em; color: var(--c-cyan-soft); }
::selection { background: var(--c-cyan); color: var(--c-ink); }

.t-editorial { font-family: var(--font-serif); font-weight: 400; letter-spacing: 0.01em; line-height: 1.7; }
.t-mono { font-family: var(--font-mono); font-size: 12px; letter-spacing: 0.16em; text-transform: uppercase; }
.mono-index { display: inline-block; margin-bottom: 14px; font-family: var(--font-mono); font-size: 12px; letter-spacing: 0.2em; color: var(--c-cyan); }
.lede { max-width: 62ch; font-size: var(--fz-19); line-height: 1.8; color: #C6D3E1; }
.muted { color: var(--c-mist); }

/* ---------- 4. 页面骨架 ---------- */
#main-content { display: block; scroll-margin-top: 96px; }
.page-shell {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(28px, 5vw, 72px) var(--gutter) clamp(56px, 8vw, 110px);
}
.section { padding-block: clamp(40px, 7vw, 96px); }
.section + .section { border-top: var(--line-soft); }
.band { padding: clamp(36px, 6vw, 88px) var(--gutter); }
.band--deep { background: var(--c-ink); }
.band--navy { background: var(--c-navy); }
.band--steel { background: var(--c-steel); }

.grid-12 { display: grid; grid-template-columns: repeat(12, minmax(0, 1fr)); gap: clamp(16px, 2vw, 28px); }
.col-3 { grid-column: span 3; }
.col-4 { grid-column: span 4; }
.col-6 { grid-column: span 6; }
.col-8 { grid-column: span 8; }
.col-12 { grid-column: span 12; }

.split { display: grid; grid-template-columns: 62fr 38fr; gap: clamp(24px, 4vw, 56px); align-items: start; }
.split--reverse { grid-template-columns: 38fr 62fr; }

.divider-line { height: 1px; background: linear-gradient(90deg, rgba(0, 229, 208, 0.55), rgba(0, 229, 208, 0)); }
.slash-band {
  height: clamp(42px, 6vw, 92px);
  background: var(--c-steel);
  clip-path: polygon(0 0, 100% 0, 100% 68%, 0 100%);
}

/* ---------- 5. 头部：框架条 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: rgba(5, 11, 24, 0.93);
  border-bottom: var(--line-frame);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
}
.site-header__inner {
  position: relative;
  display: flex;
  align-items: center;
  gap: clamp(14px, 2vw, 30px);
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--gutter);
  min-height: 72px;
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 3px;
  flex: 0 0 auto;
  padding-left: 10px;
  border-left: 2px solid var(--c-cyan);
  text-decoration: none;
}
.brand__mark { font-size: 17px; font-weight: 800; letter-spacing: 0.1em; line-height: 1.1; color: var(--c-paper); }
.brand__tag { font-family: var(--font-mono); font-size: 10px; letter-spacing: 0.22em; color: var(--c-mist); }
.brand:hover .brand__mark { color: var(--c-cyan-soft); }
.brand--footer .brand__mark { font-size: 16px; }

.site-nav { flex: 1 1 auto; min-width: 0; }
.nav-list {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: clamp(10px, 1.6vw, 26px);
  margin: 0;
  padding: 0;
  list-style: none;
}
.nav-item { flex: 0 0 auto; }
.nav-item:last-child { margin-left: clamp(8px, 3vw, 52px); }
.nav-link {
  position: relative;
  display: inline-block;
  padding: 6px 0;
  font-size: 14px;
  letter-spacing: 0.03em;
  white-space: nowrap;
  color: var(--c-mist);
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--c-cyan);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.24s var(--ease-out);
}
.nav-link:hover { color: var(--c-paper); }
.nav-link:hover::after { transform: scaleX(1); }
.nav-link[aria-current="page"] { color: var(--c-cyan); }
.nav-link[aria-current="page"]::after { transform: scaleX(1); }

.utility { display: flex; align-items: center; gap: 6px; flex: 0 0 auto; margin-left: auto; }
.util-link {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 8px 11px;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--c-cyan);
  border: 1px solid rgba(0, 229, 208, 0.28);
  clip-path: polygon(0 0, calc(100% - 8px) 0, 100% 8px, 100% 100%, 0 100%);
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out), border-color 0.2s var(--ease-out);
}
.util-link:hover { background: rgba(0, 229, 208, 0.12); border-color: var(--c-cyan); color: var(--c-cyan-soft); }
.util-link__icon { flex: 0 0 auto; }

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--c-paper);
  border: 1px solid rgba(0, 229, 208, 0.30);
  clip-path: polygon(0 0, calc(100% - 8px) 0, 100% 8px, 100% 100%, 0 100%);
  cursor: pointer;
}
.nav-toggle[aria-expanded="true"] { background: rgba(0, 229, 208, 0.14); border-color: var(--c-cyan); color: var(--c-cyan-soft); }
.nav-toggle__bars { display: inline-flex; flex-direction: column; gap: 4px; width: 16px; }
.nav-toggle__bars i { display: block; height: 1.5px; background: currentColor; transition: transform 0.2s var(--ease-out), opacity 0.2s var(--ease-out); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(1) { transform: translateY(5.5px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(3) { transform: translateY(-5.5px) rotate(-45deg); }

.scroll-meter {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  overflow: hidden;
  background: rgba(124, 243, 230, 0.08);
}
.scroll-meter__fill {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--c-cyan), var(--c-cyan-soft));
  transition: width 0.12s linear;
}

/* ---------- 6. 页脚：索引板 ---------- */
.site-footer {
  background: var(--c-navy);
  border-top: var(--line-frame);
  color: var(--c-mist);
  margin-top: clamp(40px, 6vw, 90px);
}
.site-footer__inner {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(36px, 5vw, 72px) var(--gutter) clamp(24px, 3vw, 36px);
}
.footer-top { display: grid; grid-template-columns: minmax(240px, 1.25fr) 3fr; gap: clamp(28px, 4vw, 64px); }
.footer-note { max-width: 34ch; margin: 14px 0 18px; font-size: 14px; line-height: 1.8; color: var(--c-mist); }
.footer-contact { display: grid; gap: 8px; margin: 0; padding: 0; list-style: none; }
.contact-item { display: grid; grid-template-columns: 74px 1fr; gap: 10px; font-size: 13px; line-height: 1.7; }
.contact-item__key { padding-top: 2px; font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.14em; color: rgba(167, 182, 200, 0.72); }
.contact-item__val { color: var(--c-paper); word-break: break-word; }

.footer-domains { display: grid; grid-template-columns: repeat(4, minmax(120px, 1fr)); gap: clamp(18px, 2.4vw, 34px); }
.footer-group__title { margin: 0 0 14px; font-size: 13px; font-weight: 700; letter-spacing: 0.1em; color: var(--c-paper); }
.footer-group__title a { color: inherit; border-bottom: 1px solid rgba(0, 229, 208, 0.4); }
.footer-group__title a:hover { color: var(--c-cyan-soft); border-bottom-color: var(--c-cyan-soft); }
.index-list, .link-list { display: grid; gap: 9px; margin: 0; padding: 0; list-style: none; }
.index-item { display: flex; gap: 9px; font-size: 13.5px; line-height: 1.6; color: var(--c-mist); }
.index-num { padding-top: 2px; font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.06em; color: rgba(0, 229, 208, 0.68); }
.link-list a { font-size: 13.5px; color: var(--c-mist); border-bottom: 1px solid transparent; }
.link-list a:hover { color: var(--c-cyan-soft); border-bottom-color: rgba(124, 243, 230, 0.5); }

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: clamp(26px, 5vw, 72px);
  margin-top: clamp(30px, 4vw, 56px);
  padding-top: clamp(24px, 3vw, 34px);
  border-top: var(--line-soft);
}
.footer-legal { margin-left: auto; min-width: 140px; }

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 22px;
  margin-top: clamp(26px, 3.4vw, 44px);
  padding-top: 16px;
  border-top: 1px solid rgba(167, 182, 200, 0.12);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  color: rgba(167, 182, 200, 0.82);
}
.footer-bottom__meta { display: flex; flex-wrap: wrap; gap: 6px 18px; }
.footer-version { color: var(--c-cyan); }
.footer-copy { color: rgba(244, 247, 250, 0.7); }

/* ---------- 7. 通用组件 ---------- */
.skip-link {
  position: absolute;
  left: 50%;
  top: -64px;
  z-index: 95;
  transform: translateX(-50%);
  padding: 10px 18px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--c-ink);
  background: var(--c-cyan);
  transition: top 0.18s var(--ease-out);
}
.skip-link:focus { top: 8px; color: var(--c-ink); }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 22px;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.04em;
  border: 1px solid transparent;
  cursor: pointer;
  clip-path: polygon(0 0, calc(100% - 10px) 0, 100% 10px, 100% 100%, 0 100%);
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out), border-color 0.2s var(--ease-out);
}
.btn--primary { color: var(--c-cyan); border-color: rgba(0, 229, 208, 0.55); }
.btn--primary:hover { color: var(--c-ink); background: var(--c-cyan); border-color: var(--c-cyan); }
.btn--accent { color: #1A0A02; background: var(--c-orange); border-color: var(--c-orange); }
.btn--accent:hover { color: #1A0A02; background: #FF9257; border-color: #FF9257; }
.btn--ghost { color: var(--c-paper); border-color: rgba(167, 182, 200, 0.4); }
.btn--ghost:hover { color: var(--c-cyan-soft); border-color: var(--c-cyan-soft); }

.crumbs { margin: 0 0 clamp(18px, 2.5vw, 28px); font-family: var(--font-mono); font-size: 12px; letter-spacing: 0.12em; color: var(--c-mist); }
.crumbs ol { display: flex; flex-wrap: wrap; gap: 8px; margin: 0; padding: 0; list-style: none; }
.crumbs li { margin: 0; }
.crumbs li::after { content: "/"; margin-left: 8px; color: rgba(167, 182, 200, 0.5); }
.crumbs li:last-child::after { display: none; }
.crumbs a { color: var(--c-mist); border-bottom: 1px solid transparent; }
.crumbs a:hover { color: var(--c-cyan-soft); border-bottom-color: var(--c-cyan-soft); }
.crumbs [aria-current="page"] { color: var(--c-paper); }

.panel {
  padding: clamp(20px, 3vw, 36px);
  background: var(--c-steel);
  box-shadow: var(--shadow-panel);
  clip-path: polygon(0 0, calc(100% - 28px) 0, 100% 28px, 100% 100%, 0 100%);
}
.panel--flat { background: var(--c-navy); box-shadow: none; }
.panel--slant { clip-path: polygon(0 0, 100% 12%, 100% 100%, 0 88%); }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 9px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--c-mist);
  border: 1px solid rgba(167, 182, 200, 0.35);
}
.tag--live { color: var(--c-amber); border-color: rgba(255, 194, 75, 0.45); }
.status-dot { display: inline-block; width: 6px; height: 6px; border-radius: 50%; background: var(--c-amber); }

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* ---------- 8. 媒体与设备容器（供页面阶段放置图片） ---------- */
.media-frame {
  position: relative;
  display: block;
  width: 100%;
  overflow: hidden;
  background: linear-gradient(135deg, var(--c-navy) 0%, var(--c-steel) 58%, #0E2C48 100%);
  clip-path: polygon(0 0, calc(100% - 32px) 0, 100% 32px, 100% 100%, 0 100%);
}
.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(0, 229, 208, 0.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 229, 208, 0.07) 1px, transparent 1px);
  background-size: 40px 40px;
}
.media-frame > img { width: 100%; height: 100%; object-fit: cover; }
.media-frame--16x9 { aspect-ratio: 16 / 9; }
.media-frame--4x3 { aspect-ratio: 4 / 3; }
.media-frame--1x1 { aspect-ratio: 1 / 1; }
.media-frame--3x4 { aspect-ratio: 3 / 4; }
.media-frame--wide { aspect-ratio: 21 / 9; }

.device-frame { position: relative; width: 100%; padding: 14px; background: var(--c-navy); border: 1px solid rgba(0, 229, 208, 0.24); }
.device-frame__label { display: block; margin-bottom: 10px; font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.16em; color: var(--c-cyan); }
.device-frame--desktop { max-width: 100%; }
.device-frame--tablet { max-width: 520px; }
.device-frame--phone { max-width: 300px; }

/* ---------- 9. 动效 ---------- */
.js [data-reveal] {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.52s var(--ease-out), transform 0.52s var(--ease-out);
  transition-delay: var(--reveal-delay, 0ms);
}
.js [data-reveal].is-visible { opacity: 1; transform: none; }

.to-top {
  position: fixed;
  right: clamp(16px, 3vw, 32px);
  bottom: clamp(16px, 3vw, 32px);
  z-index: 70;
  display: none;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  color: var(--c-cyan-soft);
  background: var(--c-steel);
  border: 1px solid rgba(0, 229, 208, 0.35);
  cursor: pointer;
  clip-path: polygon(0 0, calc(100% - 10px) 0, 100% 10px, 100% 100%, 0 100%);
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out);
}
.to-top[data-visible="true"] { display: inline-flex; }
.to-top:hover { color: var(--c-ink); background: var(--c-cyan); border-color: var(--c-cyan); }

@keyframes nav-drop {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: none; }
}

/* ---------- 10. 响应式与无障碍 ---------- */
:focus-visible { outline: 2px solid var(--c-cyan-soft); outline-offset: 3px; }

@media (max-width: 1080px) {
  .nav-list { gap: 12px; }
  .nav-link { font-size: 13px; }
  .util-link__label { display: none; }
  .util-link { padding: 9px; }
  .footer-top { grid-template-columns: 1fr; }
  .footer-domains { grid-template-columns: repeat(2, minmax(120px, 1fr)); }
}

@media (max-width: 900px) {
  body { background-position: left 12px top, right 12px top; }
  .site-header__inner { min-height: 64px; gap: 12px; }
  .nav-toggle { display: inline-flex; margin-left: 0; }
  .nav-toggle__label { display: none; }
  .site-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    display: none;
    max-height: calc(100vh - 64px);
    overflow-y: auto;
    padding: 8px var(--gutter) 20px;
    background: var(--c-navy);
    border-bottom: 1px solid rgba(0, 229, 208, 0.22);
    box-shadow: 0 26px 46px rgba(0, 0, 0, 0.55);
  }
  .site-nav[data-open="true"] { display: block; animation: nav-drop 0.22s var(--ease-out) both; }
  .nav-list { flex-direction: column; align-items: stretch; gap: 0; }
  .nav-item:last-child { margin-left: 0; }
  .nav-link { display: block; padding: 15px 0; font-size: 16px; border-bottom: 1px solid rgba(167, 182, 200, 0.14); }
  .nav-link::after { right: auto; bottom: -1px; width: 46px; }
  .split, .split--reverse { grid-template-columns: 1fr; }
  .col-3, .col-4 { grid-column: span 6; }
  .col-6, .col-8 { grid-column: span 12; }
  .footer-links { gap: 26px; }
}

@media (max-width: 640px) {
  .col-3, .col-4, .col-6 { grid-column: span 12; }
  .footer-domains { grid-template-columns: repeat(2, minmax(100px, 1fr)); }
  .contact-item { grid-template-columns: 1fr; gap: 2px; }
  .contact-item__key { padding-top: 0; }
  .footer-legal { margin-left: 0; }
  .footer-bottom { font-size: 11px; letter-spacing: 0.06em; }
}

@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;
  }
  .js [data-reveal] { opacity: 1 !important; transform: none !important; }
  .scroll-meter__fill { transition: none; }
}