/* ============================================================
   龙8手机指南 · /assets/site.css
   共享层：reset / 变量 / 中文排版 / 刊头 / 页脚 / 通用组件
   ============================================================ */

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

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

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

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

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

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

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

hr { border: 0; height: 1px; background: var(--rule); }

table { border-collapse: collapse; width: 100%; }

/* ---------- 2. 设计令牌 ---------- */
:root {
  --snow: #FAF7F2;
  --deep: #16233A;
  --vermilion: #C8352B;
  --turquoise: #1F7A6B;
  --ochre: #C08A2E;
  --ink: #1C1A17;
  --mist: #E3EDEA;
  --sand: #F2E4CE;
  --slate: #59677A;
  --white: #FFFFFF;

  --rule: rgba(28, 26, 23, .14);
  --rule-strong: rgba(28, 26, 23, .30);
  --rule-light: rgba(255, 255, 255, .18);

  --font-serif: 'Noto Serif SC', 'Source Han Serif SC', 'Songti SC', serif;
  --font-sans: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'IBM Plex Mono', ui-monospace, monospace;

  --radius: 4px;
  --gutter: clamp(16px, 4vw, 40px);
  --wrap: 1180px;
  --masthead-h: 150px;
}

/* ---------- 3. 中文排版基线 ---------- */
html { scroll-behavior: smooth; }

body {
  background: var(--snow);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  letter-spacing: .01em;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

h1, h2, h3 { font-family: var(--font-serif); font-weight: 700; letter-spacing: -.01em; }
h1 { font-size: clamp(2rem, 4.6vw, 3.4rem); line-height: 1.12; }
h2 { font-size: clamp(1.5rem, 2.8vw, 2.2rem); line-height: 1.25; }
h3 { font-size: clamp(1.15rem, 1.8vw, 1.4rem); font-weight: 600; line-height: 1.35; }
h4 { font-size: 1.0625rem; font-weight: 600; line-height: 1.5; }

strong { font-weight: 700; color: var(--ink); }
small { font-size: .8125rem; }

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

:where(section, article, div, li, h2, h3, [id])[id] {
  scroll-margin-top: calc(var(--masthead-h) + 12px);
}

#main-content { display: block; }

/* ---------- 4. 布局容器 ---------- */
.wrap { width: min(var(--wrap), calc(100% - var(--gutter) * 2)); margin-inline: auto; }
.wrap--wide { width: min(1360px, calc(100% - var(--gutter) * 2)); margin-inline: auto; }
.wrap--narrow { width: min(760px, calc(100% - var(--gutter) * 2)); margin-inline: auto; }

.section { padding-block: clamp(36px, 6vw, 76px); }
.section--tight { padding-block: clamp(22px, 3.5vw, 44px); }

.grid { display: grid; gap: clamp(16px, 2.4vw, 28px); }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--aside { grid-template-columns: minmax(0, 7fr) minmax(0, 4fr); }

/* ---------- 5. 工具类 ---------- */
.sr-only {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0 0 0 0); clip-path: inset(50%);
  white-space: nowrap; border: 0;
}

.mono {
  font-family: var(--font-mono);
  font-size: .75rem;
  letter-spacing: .08em;
  color: var(--slate);
}

.eyebrow {
  display: inline-flex; align-items: center; gap: 10px;
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .16em;
  color: var(--slate);
}
.eyebrow::before { content: ""; width: 18px; height: 2px; background: var(--vermilion); }

/* ---------- 6. 跳至主要内容 ---------- */
.site-skip {
  position: fixed; top: 0; left: 50%;
  z-index: 200;
  transform: translate(-50%, -140%);
  padding: 10px 20px;
  background: var(--deep);
  color: var(--white);
  border-radius: 0 0 var(--radius) var(--radius);
  font-family: var(--font-mono);
  font-size: .75rem;
  letter-spacing: .12em;
  transition: transform .18s ease;
}
.site-skip:focus-visible { transform: translate(-50%, 0); }

/* ---------- 7. 刊头（共享头部） ---------- */
.masthead {
  position: sticky;
  top: 0;
  z-index: 90;
  background: var(--snow);
  border-bottom: 1px solid var(--rule);
}

.masthead__progress { height: 2px; background: rgba(22, 35, 58, .10); }

.progress__fill {
  display: block;
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--turquoise) 0%, var(--ochre) 62%, var(--vermilion) 100%);
  transition: width .12s linear;
}

.masthead__inner {
  width: min(1240px, calc(100% - var(--gutter) * 2));
  margin-inline: auto;
}

.masthead__top {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 16px;
  padding-block: 16px;
  transition: padding .22s ease;
}

.masthead__left {
  display: flex; align-items: center; gap: 10px;
  justify-self: start; min-width: 0;
}

.masthead__section {
  display: none;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: .75rem;
  letter-spacing: .1em;
  color: var(--slate);
  white-space: nowrap;
}
.masthead__section::before { content: ""; width: 16px; height: 2px; background: var(--vermilion); }

.masthead__brand {
  display: flex; flex-direction: column; align-items: center; gap: 6px;
  justify-self: center; text-align: center;
}

.masthead__mark {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: clamp(1.75rem, 3.6vw, 2.55rem);
  line-height: 1.05;
  letter-spacing: .01em;
  color: var(--ink);
  transition: font-size .22s ease, color .18s ease;
}
.masthead__brand:hover .masthead__mark { color: var(--vermilion); }

.masthead__tagline {
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .14em;
  color: var(--slate);
}

.masthead__right { justify-self: end; }

/* 收窄状态 */
.masthead[data-condensed="true"] .masthead__top { padding-block: 8px; }
.masthead[data-condensed="true"] .masthead__left .tag { display: none; }
.masthead[data-condensed="true"] .masthead__section { display: inline-flex; }
.masthead[data-condensed="true"] .masthead__mark { font-size: 1.2rem; }
.masthead[data-condensed="true"] .masthead__tagline { display: none; }
.masthead[data-condensed="true"] .masthead__brand { gap: 0; }
.masthead[data-condensed="true"] .nav__link { padding-block: 9px; }

/* ---------- 8. 导航 ---------- */
.masthead__navrow {
  border-top: 1px solid var(--rule);
  border-bottom: 3px double var(--rule-strong);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.nav__list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: clamp(8px, 2.2vw, 32px);
}

.nav__link {
  position: relative;
  display: inline-block;
  padding: 13px 2px;
  font-size: .875rem;
  letter-spacing: .05em;
  color: var(--ink);
  transition: color .18s ease;
}
.nav__link::after {
  content: "";
  position: absolute; left: 0; right: 0; bottom: 9px;
  height: 2px; background: var(--vermilion);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform .2s ease;
}
.nav__link:hover { color: var(--vermilion); }
.nav__link:hover::after,
.nav__link:focus-visible::after { transform: scaleX(1); }
.nav__link[aria-current="page"] { color: var(--vermilion); font-weight: 600; }
.nav__link[aria-current="page"]::after { transform: scaleX(1); }

.nav__toggle { display: none; }

.nav__toggle-bars {
  display: block;
  width: 16px; height: 2px;
  background: currentColor;
  box-shadow: 0 -5px 0 currentColor, 0 5px 0 currentColor;
  transition: background .18s ease, box-shadow .18s ease;
}
.nav__toggle[aria-expanded="true"] .nav__toggle-bars {
  background: var(--vermilion);
  box-shadow: 0 -5px 0 var(--vermilion), 0 5px 0 var(--vermilion);
}
.nav__toggle-text { letter-spacing: .14em; }

/* ---------- 9. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(48px, 8vw, 96px);
  background: var(--deep);
  color: var(--white);
}
.site-footer::before {
  content: "";
  display: block;
  height: 6px;
  background: repeating-linear-gradient(
    90deg,
    var(--vermilion) 0 22px,
    var(--ochre) 22px 44px,
    var(--turquoise) 44px 66px,
    var(--sand) 66px 88px
  );
}

.site-footer__inner {
  width: min(1240px, calc(100% - var(--gutter) * 2));
  margin-inline: auto;
  padding-block: clamp(36px, 6vw, 64px) 22px;
}

.site-footer__grid {
  display: grid;
  grid-template-columns: 1.6fr .9fr .9fr .9fr 1.5fr;
  gap: clamp(20px, 3vw, 36px);
}

.site-footer__mark {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  font-weight: 700;
  line-height: 1.2;
  color: var(--white);
}

.site-footer__tagline {
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .12em;
  color: rgba(255, 255, 255, .62);
}

.site-footer__note {
  margin-top: 14px;
  max-width: 26em;
  font-size: .8125rem;
  line-height: 1.7;
  color: rgba(255, 255, 255, .58);
}

.site-footer__title {
  margin-bottom: 12px;
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .16em;
  color: var(--ochre);
}

.site-footer__list { display: flex; flex-direction: column; gap: 8px; }

.site-footer__link {
  font-size: .875rem;
  color: rgba(255, 255, 255, .82);
  border-bottom: 1px solid transparent;
  transition: color .18s ease, border-color .18s ease;
}
.site-footer__link:hover { color: var(--white); border-bottom-color: var(--ochre); }

.site-footer__line {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px;
  font-size: .875rem;
  line-height: 1.7;
  color: rgba(255, 255, 255, .82);
}
.site-footer__line + .site-footer__line { margin-top: 10px; }

.site-footer__label {
  font-family: var(--font-mono);
  font-size: .625rem;
  letter-spacing: .14em;
  color: rgba(255, 255, 255, .5);
}

.site-footer__value { color: var(--white); letter-spacing: .02em; }

.copy-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  border: 1px solid rgba(255, 255, 255, .28);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: .625rem;
  letter-spacing: .1em;
  color: rgba(255, 255, 255, .85);
  transition: border-color .18s ease, color .18s ease, background .18s ease;
}
.copy-btn:hover {
  border-color: var(--ochre);
  color: var(--ochre);
  background: rgba(192, 138, 46, .12);
}

.site-footer__base {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 8px 24px;
  margin-top: clamp(28px, 4vw, 44px);
  padding-top: 16px;
  border-top: 1px solid var(--rule-light);
}

.site-footer__meta {
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .08em;
  color: rgba(255, 255, 255, .55);
}
.site-footer__meta--right { color: rgba(255, 255, 255, .42); }

/* ---------- 10. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 20px;
  border: 1px solid var(--deep);
  border-radius: var(--radius);
  background: var(--deep);
  color: var(--white);
  font-size: .875rem;
  font-weight: 600;
  letter-spacing: .03em;
  line-height: 1;
  transition: background .18s ease, color .18s ease, border-color .18s ease;
}
.btn:hover { background: #0d1729; border-color: #0d1729; }

.btn--accent { background: var(--vermilion); border-color: var(--vermilion); }
.btn--accent:hover { background: #a82a22; border-color: #a82a22; }

.btn--ghost { background: transparent; color: var(--ink); border-color: var(--rule-strong); }
.btn--ghost:hover { background: var(--sand); color: var(--ink); border-color: var(--ochre); }

.btn--sm { padding: 8px 14px; font-size: .8125rem; }

/* ---------- 11. 标签 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius);
  background: var(--white);
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .08em;
  line-height: 1.6;
  color: var(--slate);
  white-space: nowrap;
}
.tag--red { color: var(--vermilion); border-color: rgba(200, 53, 43, .38); background: rgba(200, 53, 43, .07); }
.tag--green { color: var(--turquoise); border-color: rgba(31, 122, 107, .38); background: rgba(31, 122, 107, .08); }
.tag--gold { color: #8a5f18; border-color: rgba(192, 138, 46, .48); background: rgba(192, 138, 46, .13); }
.tag--dot::before { content: ""; width: 5px; height: 5px; border-radius: 50%; background: currentColor; }

/* ---------- 12. 面包屑 ---------- */
.breadcrumb {
  padding-block: 18px;
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .1em;
  color: var(--slate);
}
.breadcrumb ol { display: flex; flex-wrap: wrap; align-items: center; gap: 0 8px; }
.breadcrumb li { display: inline-flex; align-items: center; }
.breadcrumb li + li::before { content: "/"; margin-right: 8px; color: rgba(89, 103, 122, .45); }
.breadcrumb a:hover { color: var(--vermilion); }
.breadcrumb [aria-current="page"] { color: var(--ink); }

/* ---------- 13. 正文 ---------- */
.prose { font-size: 1.0625rem; line-height: 1.75; color: var(--ink); }
.prose p { max-width: 38em; }
.prose p + p { margin-top: 1em; }
.prose h2 { margin-top: 1.9em; margin-bottom: .6em; }
.prose h3 { margin-top: 1.6em; margin-bottom: .5em; }
.prose ul { display: flex; flex-direction: column; gap: 8px; margin-block: 1em; }
.prose ul li { position: relative; padding-left: 18px; max-width: 38em; }
.prose ul li::before {
  content: "";
  position: absolute; left: 0; top: .72em;
  width: 8px; height: 2px; background: var(--ochre);
}
.prose a { color: var(--turquoise); border-bottom: 1px solid rgba(31, 122, 107, .35); }
.prose a:hover { color: var(--vermilion); border-color: rgba(200, 53, 43, .4); }

.lead { font-size: 1.125rem; line-height: 1.7; color: var(--slate); max-width: 34em; }

/* ---------- 14. 章节标题 ---------- */
.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 16px;
  padding-top: 16px;
  margin-bottom: clamp(20px, 3vw, 32px);
  border-top: 1px solid var(--rule);
}
.section-head__no {
  font-family: var(--font-mono);
  font-size: .75rem;
  letter-spacing: .14em;
  color: var(--vermilion);
}
.section-head__title {
  font-family: var(--font-serif);
  font-size: clamp(1.4rem, 2.6vw, 2rem);
  line-height: 1.25;
  font-weight: 700;
}
.section-head__note {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .1em;
  color: var(--slate);
}

/* ---------- 15. 纸张卡 ---------- */
.paper {
  position: relative;
  padding: clamp(16px, 2.4vw, 26px);
  background: var(--white);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
}
.paper--sand { background: var(--sand); border-color: rgba(192, 138, 46, .3); }
.paper--stack { box-shadow: 6px 6px 0 -1px var(--snow), 6px 6px 0 0 var(--rule-strong); }

/* ---------- 16. 图片容器基础规则 ---------- */
.figure { display: flex; flex-direction: column; gap: 10px; }

.figure__frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: var(--figure-ratio, 4 / 3);
  background: var(--mist);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
}
.figure__frame > img,
.figure__frame > picture,
.figure__frame > picture > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.figure__frame--paper {
  background: linear-gradient(158deg, var(--mist) 0%, var(--snow) 58%, var(--sand) 100%);
}

.figure__cap {
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .08em;
  line-height: 1.6;
  color: var(--slate);
}

/* ---------- 17. 横向卷轴 ---------- */
.rail { position: relative; }

.rail__nav {
  display: flex;
  justify-content: flex-end;
  gap: 8px;
  margin-bottom: 10px;
}

.rail__btn {
  display: grid;
  place-items: center;
  width: 36px; height: 36px;
  border: 1px solid var(--rule-strong);
  border-radius: var(--radius);
  background: var(--white);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: .875rem;
  line-height: 1;
  transition: border-color .18s ease, color .18s ease;
}
.rail__btn:hover { border-color: var(--vermilion); color: var(--vermilion); }
.rail__btn[disabled] { opacity: .32; cursor: not-allowed; border-color: var(--rule); color: var(--slate); }

.rail__track {
  display: flex;
  gap: clamp(12px, 1.6vw, 18px);
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  padding-bottom: 12px;
  scrollbar-width: thin;
}
.rail__track > * {
  flex: 0 0 clamp(240px, 32%, 340px);
  scroll-snap-align: start;
}

/* ---------- 18. 锚点目录 ---------- */
.toc { position: sticky; top: calc(var(--masthead-h) + 12px); font-size: .875rem; }

.toc__title {
  margin-bottom: 12px;
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .14em;
  color: var(--slate);
}

.toc__list {
  display: flex;
  flex-direction: column;
  border-left: 1px solid var(--rule);
}

.toc__link {
  position: relative;
  display: block;
  padding: 7px 0 7px 14px;
  line-height: 1.5;
  color: var(--slate);
  transition: color .18s ease;
}
.toc__link::before {
  content: "";
  position: absolute; left: -1px; top: 0; bottom: 0;
  width: 2px;
  background: transparent;
  transition: background .18s ease;
}
.toc__link:hover { color: var(--ink); }
.toc__link[aria-current="true"] { color: var(--ink); font-weight: 600; }
.toc__link[aria-current="true"]::before { background: var(--vermilion); }

/* ---------- 19. 折叠问答 ---------- */
.accordion { border-top: 1px solid var(--rule); }
.accordion__item { border-bottom: 1px solid var(--rule); }

.accordion__btn {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  width: 100%;
  padding: 16px 0;
  text-align: left;
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.6;
  color: var(--ink);
}
.accordion__btn::after {
  content: "＋";
  margin-left: auto;
  font-family: var(--font-mono);
  color: var(--ochre);
}
.accordion__btn[aria-expanded="true"]::after { content: "－"; color: var(--vermilion); }

.accordion__panel { padding-bottom: 18px; color: var(--slate); }
.accordion__panel[hidden] { display: none; }

/* ---------- 20. 显现 ---------- */
html.js-ready [data-reveal] {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity .5s ease, transform .5s ease;
}
html.js-ready [data-reveal].is-in { opacity: 1; transform: none; }

/* ---------- 21. 响应式 ---------- */
@media (max-width: 1024px) {
  .site-footer__grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .site-footer__brand,
  .site-footer__contact { grid-column: span 3; }
}

@media (max-width: 900px) {
  .grid--2,
  .grid--3,
  .grid--aside { grid-template-columns: minmax(0, 1fr); }
  .toc { position: static; }
}

@media (max-width: 860px) {
  .masthead__inner { width: calc(100% - 24px); }
  .masthead__top { grid-template-columns: 1fr; gap: 0; padding-block: 12px; }
  .masthead__left,
  .masthead__right { display: none; }
  .masthead__mark { font-size: clamp(1.5rem, 6.6vw, 1.95rem); }
  .masthead__tagline { font-size: .625rem; letter-spacing: .1em; }
  .masthead[data-condensed="true"] .masthead__mark { font-size: 1.1rem; }
  .masthead[data-condensed="true"] .masthead__top { padding-block: 8px; }

  .nav { flex-direction: column; align-items: stretch; }
  .nav__toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    width: 100%;
    margin: 8px 0;
    padding: 11px;
    border: 1px solid var(--rule-strong);
    border-radius: var(--radius);
    background: var(--white);
    font-family: var(--font-mono);
    font-size: .6875rem;
    color: var(--ink);
  }
  .nav__list { display: none; }
  .nav[data-open="true"] .nav__list {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0 12px;
    padding-block: 6px 10px;
  }
  .nav__link {
    display: block;
    padding: 11px 8px;
    border-bottom: 1px solid var(--rule);
    font-size: .9375rem;
  }
  .nav__link::after { display: none; }
  .nav__link[aria-current="page"] { background: var(--sand); }

  .rail__track > * { flex: 0 0 78%; }
  .rail__nav { justify-content: flex-start; }
}

@media (max-width: 640px) {
  .site-footer__grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .site-footer__brand,
  .site-footer__contact { grid-column: span 2; }
  .site-footer__base { flex-direction: column; }
  .site-footer__meta--right { display: none; }
}

/* ---------- 22. 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .site-skip,
  .progress__fill,
  .masthead__top,
  .masthead__mark,
  .nav__link,
  .nav__link::after,
  .nav__toggle-bars,
  .btn,
  .copy-btn,
  .site-footer__link,
  .toc__link,
  .toc__link::before,
  .rail__btn { transition: none; }
  html.js-ready [data-reveal] { opacity: 1; transform: none; transition: none; }
}