/* ==========================================================================
   贝博中心 · 共享外壳样式
   reset / tokens / 中文排版 / 头部 / 页脚 / 通用组件 / 响应式
   ========================================================================== */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 28px;
}

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

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

/* ---------- 2. 设计变量 ---------- */
:root {
  /* 色彩 */
  --ink-black: #15100F;
  --thangka-red: #B23A2F;
  --thangka-deep: #7E241C;
  --gold: #D6A94A;
  --gold-light: #F0D9A0;
  --lake-blue: #2E6E8E;
  --lake-deep: #1B4257;
  --prayer-green: #356B52;
  --paper: #F6F1E7;
  --ink: #2C2622;
  --fog: #8C8178;

  /* 字体 */
  --font-display: "Source Han Serif SC", "Noto Serif SC", "Songti SC", Songti, "STSong", serif;
  --font-body: "PingFang SC", "Noto Sans SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-mono: ui-monospace, "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, monospace;

  /* 字号阶梯 */
  --fs-xs: 12px;
  --fs-sm: 14px;
  --fs-base: 17px;
  --fs-md: 22px;
  --fs-lg: 32px;
  --fs-xl: 56px;

  /* 节奏 */
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --t-fast: 220ms;
  --t-mid: 480ms;
  --t-slow: 600ms;

  /* 几何母题 */
  --cut: 14px;
  --cut-btn: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);

  /* 栅格 */
  --shell: 1280px;
  --gutter: 20px;
}

@media (min-width: 640px) { :root { --gutter: 28px; } }
@media (min-width: 900px) { :root { --gutter: 32px; } }

/* ---------- 3. 中文排版基线 ---------- */
body {
  font-family: var(--font-body);
  font-size: var(--fs-base);
  line-height: 1.8;
  color: var(--ink);
  background-color: var(--paper);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -0.02em;
}

p { max-width: 38em; }

.mono {
  font-family: var(--font-mono);
  letter-spacing: 0.04em;
  font-variant-numeric: tabular-nums;
}

/* ---------- 4. 跳转链接 ---------- */
.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 300;
  padding: 12px 22px;
  background: var(--gold);
  color: var(--ink-black);
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: 0.1em;
  clip-path: var(--cut-btn);
  transform: translateY(-220%);
  transition: transform var(--t-fast) var(--ease);
}

.skip-link:focus {
  transform: translateY(0);
}

/* ---------- 5. 头部 ---------- */
.site-header {
  position: relative;
  z-index: 40;
  color: var(--paper);
  background-color: var(--ink-black);
  background-image:
    radial-gradient(130% 150% at 6% -30%, rgba(178, 58, 47, 0.46), transparent 58%),
    radial-gradient(110% 130% at 100% -12%, rgba(46, 110, 142, 0.42), transparent 62%),
    linear-gradient(180deg, #1B4257 0%, #15100F 66%);
  border-bottom: 1px solid rgba(214, 169, 74, 0.3);
  overflow: hidden;
}

.site-header::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
  background: linear-gradient(90deg,
    var(--prayer-green) 0%,
    var(--lake-blue) 28%,
    var(--gold) 58%,
    var(--thangka-red) 100%);
  opacity: 0.85;
}

.site-header::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: repeating-linear-gradient(96deg,
    rgba(240, 217, 160, 0.05) 0 1px,
    transparent 1px 26px);
}

.header-inner {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  column-gap: 16px;
  max-width: var(--shell);
  margin: 0 auto;
  padding: 16px var(--gutter) 18px;
}

/* 品牌块 */
.header-brand {
  min-width: 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 14px;
}

.brand-mark {
  position: relative;
  flex: none;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  background: repeating-conic-gradient(from 0deg,
    var(--gold) 0deg 1.6deg,
    transparent 1.6deg 15deg);
}

.brand-mark::before {
  content: "";
  position: absolute;
  inset: 6px;
  border-radius: 50%;
  background: var(--ink-black);
  border: 1px solid rgba(214, 169, 74, 0.5);
}

.brand-mark::after {
  content: "";
  position: absolute;
  inset: 15px;
  border-radius: 50%;
  background: radial-gradient(circle at 34% 30%, var(--gold) 0%, var(--thangka-red) 72%);
}

.brand-copy {
  display: flex;
  flex-direction: column;
  gap: 5px;
  min-width: 0;
}

.brand-name {
  font-family: var(--font-display);
  font-size: 21px;
  line-height: 1.1;
  letter-spacing: 0.02em;
  color: var(--gold-light);
}

.brand-tagline {
  font-size: 11px;
  line-height: 1.4;
  letter-spacing: 0.16em;
  color: rgba(240, 217, 160, 0.6);
}

.header-note {
  display: none;
}

.header-cta {
  display: none;
}

/* 移动菜单键 */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  color: var(--gold-light);
  border: 1px solid rgba(214, 169, 74, 0.5);
  clip-path: var(--cut-btn);
  transition: background-color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

.nav-toggle:hover {
  background: rgba(214, 169, 74, 0.14);
  border-color: var(--gold);
}

.nav-toggle-bars {
  display: flex;
  flex-direction: column;
  gap: 4px;
  width: 18px;
}

.nav-toggle-bars span {
  display: block;
  height: 1.5px;
  background: currentColor;
  transition: transform var(--t-fast) var(--ease), opacity var(--t-fast) var(--ease);
}

.site-header[data-open] .nav-toggle-bars span:nth-child(1) { transform: translateY(5.5px) rotate(45deg); }
.site-header[data-open] .nav-toggle-bars span:nth-child(2) { opacity: 0; }
.site-header[data-open] .nav-toggle-bars span:nth-child(3) { transform: translateY(-5.5px) rotate(-45deg); }

.nav-toggle-label {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
}

/* 导航 */
.site-nav {
  display: none;
  grid-column: 1 / -1;
  margin-top: 16px;
  padding-top: 8px;
  border-top: 1px solid rgba(214, 169, 74, 0.26);
}

.site-header[data-open] .site-nav { display: block; }

.nav-list {
  display: flex;
  flex-direction: column;
}

.nav-link {
  display: flex;
  align-items: baseline;
  justify-content: flex-start;
  gap: 12px;
  padding: 13px 2px;
  font-size: 15px;
  letter-spacing: 0.05em;
  color: rgba(246, 241, 231, 0.82);
  border-bottom: 1px solid rgba(214, 169, 74, 0.14);
  transition: color var(--t-fast) var(--ease), padding-left var(--t-fast) var(--ease);
}

.nav-link:hover {
  color: var(--gold-light);
}

.nav-index {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--gold);
  opacity: 0.75;
}

.nav-label { position: relative; }

.nav-link[aria-current="page"] {
  color: var(--gold-light);
}

.nav-link[aria-current="page"] .nav-label::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -5px;
  height: 1px;
  background: var(--gold);
}

.nav-link[aria-current="page"] .nav-index {
  opacity: 1;
  color: var(--gold-light);
}

/* ---------- 6. 页脚 ---------- */
.site-footer {
  position: relative;
  color: rgba(246, 241, 231, 0.82);
  background-color: var(--ink-black);
  background-image: linear-gradient(180deg, #1B4257 0%, #15100F 42%);
}

.site-footer::before {
  content: "";
  display: block;
  height: 3px;
  background: linear-gradient(90deg,
    var(--thangka-red) 0%,
    var(--gold) 34%,
    var(--lake-blue) 68%,
    var(--prayer-green) 100%);
  opacity: 0.9;
}

.footer-inner {
  display: grid;
  gap: 44px;
  max-width: var(--shell);
  margin: 0 auto;
  padding: 52px var(--gutter) 40px;
}

.footer-sign {
  margin-top: 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: rgba(240, 217, 160, 0.55);
}

.brand--footer .brand-name { font-size: 19px; }

.footer-cols {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(118px, 1fr));
  gap: 32px 24px;
}

.footer-col-title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 400;
  letter-spacing: 0.22em;
  color: var(--gold);
  padding-bottom: 10px;
  border-bottom: 1px solid rgba(214, 169, 74, 0.24);
}

.footer-link {
  display: block;
  padding: 7px 0;
  font-size: 14px;
  letter-spacing: 0.04em;
  color: rgba(246, 241, 231, 0.72);
  transition: color var(--t-fast) var(--ease), transform var(--t-fast) var(--ease);
}

.footer-link:hover {
  color: var(--gold-light);
  transform: translateX(3px);
}

.footer-contact {
  border-top: 1px solid rgba(214, 169, 74, 0.2);
  border-bottom: 1px solid rgba(214, 169, 74, 0.2);
  background: rgba(21, 16, 15, 0.5);
}

.footer-contact-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 32px;
  max-width: var(--shell);
  margin: 0 auto;
  padding: 22px var(--gutter);
}

.contact-line {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.03em;
  line-height: 1.7;
  color: rgba(240, 217, 160, 0.8);
}

.footer-base {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 10px 24px;
  max-width: var(--shell);
  margin: 0 auto;
  padding: 22px var(--gutter) 92px;
}

.footer-copy,
.footer-icp {
  max-width: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: rgba(140, 129, 120, 0.95);
}

/* ---------- 7. 返回顶部 ---------- */
.to-top {
  position: fixed;
  right: 18px;
  bottom: 18px;
  z-index: 90;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1px;
  width: 52px;
  height: 52px;
  border-radius: 50%;
  color: var(--gold-light);
  background: var(--ink-black);
  border: 1px solid rgba(214, 169, 74, 0.4);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity var(--t-fast) var(--ease),
              transform var(--t-fast) var(--ease),
              visibility var(--t-fast) linear;
}

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

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

.to-top-ring {
  --progress: 0deg;
  position: absolute;
  inset: -2px;
  border-radius: 50%;
  background: conic-gradient(from -90deg,
    var(--gold) var(--progress),
    rgba(214, 169, 74, 0.16) var(--progress));
  -webkit-mask: radial-gradient(farthest-side, transparent calc(100% - 3px), #000 calc(100% - 3px));
  mask: radial-gradient(farthest-side, transparent calc(100% - 3px), #000 calc(100% - 3px));
  pointer-events: none;
}

.to-top-text {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  line-height: 1;
}

/* ---------- 8. 通用按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 13px 26px;
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.08em;
  line-height: 1.4;
  border: 1px solid transparent;
  clip-path: var(--cut-btn);
  transition: background-color var(--t-fast) var(--ease),
              color var(--t-fast) var(--ease),
              border-color var(--t-fast) var(--ease);
}

.btn:focus-visible {
  outline: none;
  box-shadow: inset 0 0 0 2px var(--gold-light);
}

.btn--primary {
  background: var(--thangka-red);
  color: var(--paper);
}

.btn--primary:hover {
  background: var(--thangka-deep);
}

.btn--gold {
  background: var(--gold);
  color: var(--ink-black);
}

.btn--gold:hover {
  background: var(--gold-light);
}

.btn--outline {
  border-color: rgba(214, 169, 74, 0.55);
  color: var(--gold-light);
}

.btn--outline:hover {
  background: rgba(214, 169, 74, 0.14);
  border-color: var(--gold);
}

.btn--ink {
  border-color: var(--fog);
  color: var(--ink);
}

.btn--ink:hover {
  border-color: var(--thangka-red);
  color: var(--thangka-red);
}

.btn--sm {
  padding: 9px 18px;
  font-size: 13px;
  letter-spacing: 0.06em;
}

/* ---------- 9. 布局与容器 ---------- */
.shell {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.split {
  display: grid;
  gap: 40px;
}

.island {
  padding: 40px 24px;
  background: var(--paper);
}

.split--reverse > :first-child { order: 2; }

/* ---------- 10. 通用排版组件 ---------- */
.eyebrow {
  display: flex;
  align-items: center;
  gap: 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--thangka-red);
}

.eyebrow::before {
  content: "";
  width: 32px;
  height: 1px;
  background: var(--gold);
}

.section-rule {
  height: 1px;
  border: 0;
  background: linear-gradient(90deg,
    var(--thangka-red) 0%,
    var(--gold) 22%,
    var(--fog) 22.2%,
    transparent 100%);
  transform: skewY(-0.6deg);
  transform-origin: left center;
  opacity: 0.55;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 11px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  line-height: 1.7;
  color: var(--thangka-red);
  border: 1px solid rgba(178, 58, 47, 0.4);
  background: rgba(178, 58, 47, 0.07);
}

.tag--lake {
  color: var(--lake-blue);
  border-color: rgba(46, 110, 142, 0.42);
  background: rgba(46, 110, 142, 0.08);
}

.tag--green {
  color: var(--prayer-green);
  border-color: rgba(53, 107, 82, 0.42);
  background: rgba(53, 107, 82, 0.09);
}

/* ---------- 11. 面包屑 ---------- */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
}

.breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  color: var(--fog);
}

.breadcrumb-list > li + li::before {
  content: "/";
  margin-right: 8px;
  color: rgba(140, 129, 120, 0.6);
}

.breadcrumb-list > li[aria-current="page"] {
  color: var(--thangka-red);
}

.breadcrumb-link {
  color: var(--fog);
  border-bottom: 1px solid transparent;
  transition: color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

.breadcrumb-link:hover {
  color: var(--lake-blue);
  border-bottom-color: var(--lake-blue);
}

/* ---------- 12. 图片占位容器 ---------- */
.media-frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 10;
  background-color: var(--lake-deep);
  background-image:
    radial-gradient(120% 120% at 20% 0%, rgba(46, 110, 142, 0.55), transparent 60%),
    linear-gradient(160deg, var(--lake-deep) 0%, var(--ink-black) 100%);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--cut)), calc(100% - var(--cut)) 100%, 0 100%);
}

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

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(180deg, rgba(21, 16, 15, 0) 48%, rgba(21, 16, 15, 0.58) 100%);
}

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

/* ---------- 13. 入场显现 ---------- */
.js [data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity var(--t-mid) var(--ease), transform var(--t-mid) var(--ease);
}

.js [data-reveal][data-revealed] {
  opacity: 1;
  transform: none;
}

/* ---------- 14. 章节时间轴 ---------- */
.toc {
  display: none;
}

.toc-title {
  margin-bottom: 16px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.22em;
  color: var(--fog);
}

.toc-link {
  position: relative;
  display: block;
  padding: 7px 0 7px 18px;
  font-size: 13px;
  letter-spacing: 0.04em;
  color: rgba(44, 38, 34, 0.62);
  border-left: 1px solid rgba(140, 129, 120, 0.4);
  transition: color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

.toc-link:hover { color: var(--thangka-red); }

.toc-link[aria-current="location"] {
  color: var(--thangka-red);
  border-left-color: var(--thangka-red);
  font-weight: 600;
}

/* ---------- 15. 平板 ---------- */
@media (min-width: 640px) {
  .header-note {
    display: block;
    margin-top: 16px;
    font-family: var(--font-mono);
    font-size: 11.5px;
    letter-spacing: 0.08em;
    line-height: 1.7;
    color: rgba(240, 217, 160, 0.55);
  }

  .island { padding: 52px 40px; }

  .split { gap: 48px; }

  .footer-inner { padding-top: 60px; }
}

/* ---------- 16. 桌面 ---------- */
@media (min-width: 900px) {
  .header-inner {
    grid-template-columns: minmax(0, 1fr) minmax(210px, 260px);
    align-items: start;
    column-gap: 48px;
    padding-top: 26px;
    padding-bottom: 28px;
  }

  .header-cta {
    display: inline-flex;
    margin-top: 18px;
  }

  .nav-toggle { display: none; }

  .site-nav {
    display: block;
    grid-column: auto;
    justify-self: end;
    width: 100%;
    margin-top: 0;
    padding-top: 0;
    border-top: 0;
  }

  .nav-link {
    justify-content: flex-end;
    gap: 10px;
    padding: 5px 0;
    font-size: 13.5px;
    border-bottom: 0;
  }

  .nav-link:hover { padding-left: 0; }

  .brand-name { font-size: 23px; }

  .split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: 56px;
  }

  .split--reverse {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  }

  .split--reverse > :first-child { order: 0; }

  .island { padding: 80px; }

  .footer-inner {
    grid-template-columns: minmax(0, 1.25fr) minmax(0, 2fr);
    gap: 56px;
    padding-top: 76px;
    padding-bottom: 52px;
  }

  .toc { display: block; }

  .to-top {
    right: 26px;
    bottom: 26px;
    width: 56px;
    height: 56px;
  }
}

@media (min-width: 1200px) {
  .brand-tagline { font-size: 11.5px; }

  .nav-link { font-size: 14px; padding: 6px 0; }
}

/* ---------- 17. 降级动效 ---------- */
@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;
  }

  .js [data-reveal] {
    opacity: 1;
    transform: none;
  }

  .to-top {
    transform: none;
  }

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