/* ============================================================
   6686官方版 · /assets/site.css
   共享外壳：重置 / 变量 / 中文排版 / 头部 / 页脚 / 通用组件
   ============================================================ */

/* ---------- 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, ul, ol, li, figure, figcaption, blockquote, dl, dd {
  margin: 0;
}

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

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

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

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

img { height: auto; }

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

:focus-visible {
  outline: 2px solid #E4A177;
  outline-offset: 2px;
}

/* ---------- 2. 设计变量 ---------- */
:root {
  /* 矿物色体系 */
  --ink:        #0F2233;
  --ink-2:      #1B3348;
  --ink-deep:   #07121B;
  --clay:       #C05A2B;
  --clay-soft:  #E4A177;
  --cream:      #F6F0E3;
  --sand:       #E8DFCC;
  --mist:       #7E8F80;
  --moss:       #55663F;
  --stone:      #97A2AB;

  /* 语义映射 */
  --bg:         var(--ink);
  --fg:         var(--cream);
  --line:       rgba(151, 162, 171, .26);
  --line-strong:rgba(151, 162, 171, .46);
  --line-dark:  rgba(7, 18, 27, .14);

  /* 字体 */
  --f-head: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
            "Source Han Sans SC", "Noto Sans CJK SC", sans-serif;
  --f-body: "Songti SC", "SimSun", "Source Han Serif SC",
            "Noto Serif CJK SC", Georgia, serif;
  --f-mono: "SFMono-Regular", Menlo, Consolas, "Liberation Mono", ui-monospace, monospace;

  /* 字号阶梯 */
  --fs-12: 12px;
  --fs-14: 14px;
  --fs-16: 16px;
  --fs-20: 20px;
  --fs-28: 28px;
  --fs-40: 40px;
  --fs-64: 64px;

  /* 布局与节奏 */
  --w: 1200px;
  --w-narrow: 860px;
  --ease: cubic-bezier(.22, .68, .28, 1);
  --head-h: 84px;
}

/* ---------- 3. 页面基底：深墨蓝蓝图网格 ---------- */
body {
  min-height: 100vh;
  background-color: var(--bg);
  background-image:
    linear-gradient(rgba(151, 162, 171, .062) 1px, transparent 1px),
    linear-gradient(90deg, rgba(151, 162, 171, .062) 1px, transparent 1px);
  background-size: 72px 72px;
  background-position: center top;
  color: var(--fg);
  font-family: var(--f-body);
  font-size: var(--fs-16);
  line-height: 1.9;
  letter-spacing: .01em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

#main-content { outline: none; }

/* ---------- 4. 容器与节奏 ---------- */
.shell {
  width: min(100% - 40px, var(--w));
  margin-inline: auto;
}

.shell--narrow {
  width: min(100% - 40px, var(--w-narrow));
  margin-inline: auto;
}

.section { padding: 72px 0; }
.section--tight { padding: 40px 0; }

/* ---------- 5. 跳转链接 ---------- */
.skip-link {
  position: fixed;
  top: -72px;
  left: 20px;
  z-index: 300;
  display: inline-flex;
  align-items: center;
  height: 44px;
  padding: 0 20px;
  background: var(--clay);
  color: var(--ink-deep);
  font: 800 var(--fs-14) / 1 var(--f-head);
  letter-spacing: .04em;
  transition: top .2s var(--ease);
}

.skip-link:focus { top: 14px; }

/* ---------- 6. 阅读进度条 ---------- */
.read-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  z-index: 260;
  background: rgba(151, 162, 171, .16);
  pointer-events: none;
}

.read-progress__bar {
  display: block;
  width: 0;
  height: 100%;
  background: var(--clay);
  transition: width .12s linear;
}

/* ---------- 7. 头部：三枚浮岛 ---------- */
.site-head {
  position: sticky;
  top: 0;
  z-index: 200;
  padding: 16px 0;
  background: var(--ink);
  border-bottom: 1px solid transparent;
  transition: padding .28s var(--ease), border-color .28s var(--ease);
}

.site-head[data-shrink] {
  padding: 8px 0;
  border-bottom-color: var(--line);
}

.site-head__inner {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* 品牌浮岛 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  height: 52px;
  padding: 0 18px;
  flex: 0 0 auto;
  background: var(--ink-2);
  border: 1px solid var(--line-strong);
  transition: border-color .24s var(--ease), background-color .24s var(--ease);
}

.brand:hover { border-color: var(--clay-soft); }

.brand__mark {
  font: 700 var(--fs-12) / 1 var(--f-mono);
  letter-spacing: .1em;
  color: var(--clay-soft);
}

.brand__text {
  font: 800 17px / 1 var(--f-head);
  letter-spacing: .01em;
  color: var(--cream);
  white-space: nowrap;
}

/* 栏目胶囊岛 */
.nav-pill {
  margin-left: auto;
  display: flex;
  align-items: center;
  height: 52px;
  padding: 0 6px;
  background: var(--ink-2);
  border: 1px solid var(--line-strong);
}

.nav-pill__list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.nav-pill__list a {
  display: block;
  height: 38px;
  line-height: 36px;
  padding: 0 15px;
  border: 1px solid transparent;
  color: var(--stone);
  font: 600 var(--fs-14) / 1 var(--f-head);
  letter-spacing: .02em;
  white-space: nowrap;
  transition: color .22s var(--ease),
              border-color .22s var(--ease),
              background-color .22s var(--ease);
}

.nav-pill__list a:hover {
  color: var(--cream);
  border-color: var(--line-strong);
}

.nav-pill__list a[aria-current="page"] {
  color: var(--clay-soft);
  border-color: var(--clay);
  background: rgba(192, 90, 43, .14);
}

/* 右侧工具槽 */
.head-tools {
  display: flex;
  align-items: center;
  gap: 8px;
  flex: 0 0 auto;
}

.quick-pill {
  display: inline-flex;
  align-items: center;
  height: 52px;
  padding: 0 22px;
  background: var(--clay);
  border: 1px solid var(--clay);
  color: var(--ink-deep);
  font: 800 var(--fs-14) / 1 var(--f-head);
  letter-spacing: .05em;
  white-space: nowrap;
  transition: background-color .22s var(--ease), border-color .22s var(--ease);
}

.quick-pill:hover {
  background: var(--clay-soft);
  border-color: var(--clay-soft);
}

/* 移动导航按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  height: 52px;
  padding: 0 16px;
  background: var(--ink-2);
  border: 1px solid var(--line-strong);
  color: var(--cream);
  font: 700 13px / 1 var(--f-head);
  letter-spacing: .06em;
  transition: border-color .22s var(--ease), color .22s var(--ease);
}

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

.nav-toggle__icon {
  position: relative;
  display: block;
  width: 16px;
  height: 11px;
}

.nav-toggle__icon::before,
.nav-toggle__icon::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 1.5px;
  background: currentColor;
  transition: transform .22s var(--ease), top .22s var(--ease), bottom .22s var(--ease);
}

.nav-toggle__icon::before { top: 1px; }
.nav-toggle__icon::after { bottom: 1px; }

.nav-toggle[aria-expanded="true"] .nav-toggle__icon::before {
  top: 4.5px;
  transform: rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__icon::after {
  bottom: 5px;
  transform: rotate(-45deg);
}

/* ---------- 8. 移动端导航面板 ---------- */
@media (max-width: 1000px) {
  .nav-toggle { display: inline-flex; }

  .nav-pill {
    position: fixed;
    top: calc(var(--head-offset, var(--head-h)) + 8px);
    left: 20px;
    right: 20px;
    z-index: 210;
    display: block;
    height: auto;
    max-height: calc(100vh - 140px);
    overflow-y: auto;
    margin: 0;
    padding: 10px;
    background: var(--ink-2);
    border: 1px solid var(--line-strong);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: opacity .24s var(--ease),
                transform .24s var(--ease),
                visibility .24s linear;
  }

  .nav-pill[data-open] {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }

  .nav-pill__list {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
  }

  .nav-pill__list a {
    height: 46px;
    line-height: 44px;
    padding: 0 14px;
    font-size: var(--fs-16);
  }
}

@media (max-width: 720px) {
  .shell,
  .shell--narrow { width: min(100% - 28px, var(--w)); }

  .site-head { padding: 10px 0; }

  .brand { height: 46px; padding: 0 14px; }
  .brand__text { font-size: 15px; }
  .brand__mark { display: none; }

  .head-tools .quick-pill { display: none; }
  .nav-toggle { height: 46px; padding: 0 13px; }
  .nav-toggle__text { display: none; }

  .nav-pill { left: 14px; right: 14px; }

  .section { padding: 48px 0; }
  .section--tight { padding: 28px 0; }
}

/* ---------- 9. 页脚 ---------- */
.site-foot {
  margin-top: 104px;
  padding: 64px 0 32px;
  background: var(--ink-deep);
  border-top: 1px solid var(--line-strong);
  color: var(--stone);
}

.foot-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1.4fr;
  gap: 44px 32px;
}

.foot-brand__name {
  font: 900 var(--fs-28) / 1.1 var(--f-head);
  letter-spacing: -.01em;
  color: var(--cream);
}

.foot-brand__desc {
  margin-top: 16px;
  max-width: 34ch;
  font: 400 var(--fs-14) / 1.95 var(--f-body);
  color: var(--stone);
}

.foot-col__title {
  padding-bottom: 12px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--line);
  font: 700 var(--fs-12) / 1 var(--f-mono);
  letter-spacing: .16em;
  color: var(--clay-soft);
}

.foot-col__list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.foot-col__list a {
  font: 400 var(--fs-14) / 1.7 var(--f-body);
  color: var(--sand);
  border-bottom: 1px solid transparent;
  transition: color .2s var(--ease), border-color .2s var(--ease);
}

.foot-col__list a:hover {
  color: var(--clay-soft);
  border-bottom-color: var(--clay-soft);
}

.foot-col__list--plain li {
  font: 400 var(--fs-14) / 1.8 var(--f-body);
  color: var(--stone);
}

.foot-col__list--plain .mono { color: var(--sand); }

.foot-col__more { margin-top: 18px; }

.foot-col__more a {
  display: inline-flex;
  align-items: center;
  height: 38px;
  padding: 0 16px;
  border: 1px solid var(--line-strong);
  color: var(--cream);
  font: 700 13px / 1 var(--f-head);
  letter-spacing: .04em;
  transition: border-color .22s var(--ease), color .22s var(--ease);
}

.foot-col__more a:hover {
  border-color: var(--clay-soft);
  color: var(--clay-soft);
}

.foot-base {
  margin-top: 52px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px 28px;
  font: 400 13px / 1.8 var(--f-body);
  color: var(--stone);
}

.foot-base__legal {
  font-family: var(--f-mono);
  font-size: var(--fs-12);
  letter-spacing: .08em;
  color: var(--mist);
}

.foot-base__note { color: var(--stone); }

@media (max-width: 1000px) {
  .foot-grid { grid-template-columns: 1fr 1fr; }
  .foot-brand { grid-column: 1 / -1; }
}

@media (max-width: 620px) {
  .site-foot { margin-top: 64px; padding-top: 44px; }
  .foot-grid { grid-template-columns: 1fr; gap: 34px; }
}

/* ---------- 10. 通用排版与标签 ---------- */
.coord {
  font: 500 11px / 1 var(--f-mono);
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--stone);
}

.mono {
  font-family: var(--f-mono);
  font-size: .94em;
  letter-spacing: .05em;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font: 600 var(--fs-12) / 1 var(--f-mono);
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--clay-soft);
}

.eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  background: currentColor;
}

.sec-num {
  font: 800 clamp(40px, 6vw, 64px) / .9 var(--f-mono);
  letter-spacing: -.02em;
  font-variant-numeric: tabular-nums;
  color: var(--clay);
  flex: 0 0 auto;
}

.prose {
  max-width: 62ch;
  font: 400 17px / 1.9 var(--f-body);
  color: inherit;
}

.prose + .prose { margin-top: 18px; }

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

.panel .rule { background: var(--line-dark); }

.tag {
  display: inline-flex;
  align-items: center;
  height: 26px;
  padding: 0 10px;
  border: 1px solid var(--line-strong);
  color: var(--mist);
  font: 600 var(--fs-12) / 1 var(--f-mono);
  letter-spacing: .08em;
}

.tag--clay { color: var(--clay-soft); border-color: rgba(192, 90, 43, .55); }
.tag--moss { color: var(--moss); border-color: rgba(85, 102, 63, .5); }

/* ---------- 11. 面板 ---------- */
.panel {
  background: var(--cream);
  color: var(--ink-deep);
  border: 1px solid rgba(7, 18, 27, .1);
  padding: clamp(24px, 4vw, 56px);
}

.panel--sand {
  background: var(--sand);
  color: var(--ink-deep);
}

.panel .eyebrow { color: var(--clay); }
.panel .coord { color: var(--mist); }
.panel .sec-num { color: var(--clay); }
.panel .prose { color: var(--ink-deep); }

/* ---------- 12. 章节头 ---------- */
.block-head {
  display: flex;
  align-items: flex-start;
  gap: 22px;
}

.block-head__title {
  font: 800 clamp(20px, 2.5vw, var(--fs-28)) / 1.28 var(--f-head);
  letter-spacing: -.005em;
  color: inherit;
}

.block-head__meta {
  margin-top: 10px;
  font: 400 var(--fs-14) / 1.8 var(--f-body);
  color: var(--stone);
}

.panel .block-head__meta { color: var(--mist); }

@media (max-width: 620px) {
  .block-head { gap: 14px; }
  .block-head__title { font-size: var(--fs-20); }
}

/* ---------- 13. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  height: 50px;
  padding: 0 26px;
  border: 1px solid transparent;
  font: 800 15px / 1 var(--f-head);
  letter-spacing: .04em;
  cursor: pointer;
  transition: background-color .22s var(--ease),
              color .22s var(--ease),
              border-color .22s var(--ease);
}

.btn--clay {
  background: var(--clay);
  border-color: var(--clay);
  color: var(--ink-deep);
}

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

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

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

.panel .btn--ghost {
  border-color: rgba(15, 34, 51, .38);
  color: var(--ink);
}

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

.btn__arrow {
  font-family: var(--f-mono);
  font-size: .92em;
  letter-spacing: 0;
}

/* ---------- 14. 面包屑 ---------- */
.crumbs { padding: 26px 0 0; }

.crumbs ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  font: 500 var(--fs-12) / 1 var(--f-mono);
  letter-spacing: .08em;
  color: var(--stone);
}

.crumbs li + li::before {
  content: "/";
  margin: 0 10px;
  color: var(--line-strong);
}

.crumbs a { transition: color .2s var(--ease); }
.crumbs a:hover { color: var(--clay-soft); }

/* ---------- 15. 网格 ---------- */
.grid {
  display: grid;
  gap: 24px;
}

.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }

@media (max-width: 980px) {
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 700px) {
  .grid--2,
  .grid--3 { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- 16. 图片容器（供页面阶段放置图片） ---------- */
.frame {
  position: relative;
  display: block;
  overflow: hidden;
  background: var(--ink-2);
  border: 1px solid var(--line-strong);
}

.frame::after {
  content: "";
  position: absolute;
  inset: 9px;
  border: 1px solid rgba(246, 240, 227, .12);
  pointer-events: none;
}

.frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.frame--4x3 { aspect-ratio: 4 / 3; }
.frame--16x9 { aspect-ratio: 16 / 9; }
.frame--1x1 { aspect-ratio: 1 / 1; }

.frame__cap {
  position: absolute;
  left: 0;
  bottom: 0;
  z-index: 2;
  max-width: 100%;
  padding: 10px 15px;
  background: rgba(7, 18, 27, .8);
  color: var(--cream);
  font: 500 var(--fs-12) / 1.4 var(--f-mono);
  letter-spacing: .06em;
}

.panel .frame {
  background: var(--sand);
  border-color: rgba(15, 34, 51, .18);
}

.panel .frame::after { border-color: rgba(15, 34, 51, .1); }

/* ---------- 17. 动效协议 ---------- */
.reveal-hidden { opacity: 0; }

@keyframes riseIn {
  from { opacity: 0; transform: translateY(14px); }
  to   { opacity: 1; transform: translateY(0); }
}

.reveal-in { animation: riseIn .52s var(--ease) both; }

/* ---------- 18. 返回顶部 ---------- */
.to-top {
  position: fixed;
  right: 22px;
  bottom: 22px;
  z-index: 220;
  width: 46px;
  height: 46px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--ink-2);
  border: 1px solid var(--line-strong);
  color: var(--clay-soft);
  font: 700 17px / 1 var(--f-mono);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity .24s var(--ease),
              transform .24s var(--ease),
              visibility .24s linear,
              border-color .22s var(--ease);
}

.to-top[data-show] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.to-top:hover { border-color: var(--clay-soft); }

@media (max-width: 620px) {
  .to-top { right: 14px; bottom: 14px; width: 42px; height: 42px; }
}

/* ---------- 19. 降低动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }

  .reveal-hidden { opacity: 1; }
  .reveal-in { animation: none; }
}