:root {
  --color-surface: #f8f8f9;
  --color-surface-alt: #efeff1;
  --color-surface-deep: #e2e3e5;
  --color-ink: #444850;
  --color-ink-soft: #686d78;
  --color-ink-muted: #787d87;
  --color-line: #d8d8db;
  --color-primary: #496bb6;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e0e4f0;
  --color-accent: #c0541b;
  --color-accent-ink: #ffffff;
  --color-highlight: #eedad1;
  --color-focus: #bd4b0f;
  --color-contrast-surface: #14171e;
  --color-contrast-ink: #e4e5e7;
  --color-contrast-line: #42444a;
  --color-contrast-accent: #e0621f;
  --overlay-scrim: linear-gradient(180deg, rgba(20, 23, 30, 0.35) 0%, rgba(20, 23, 30, 0.72) 55%, rgba(20, 23, 30, 0.92) 100%);
  --font-heading: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-body: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --text-xs: 12.9px;
  --text-sm: 15.5px;
  --text-base: 17px;
  --text-lg: 20.4px;
  --text-xl: 24.5px;
  --text-2xl: 29.4px;
  --text-3xl: 35.3px;
  --text-4xl: 42.3px;
  --text-display: clamp(34px, 4.8vw, 61px);
  --text-figure: clamp(28px, 3.4vw, 44px);
  --weight-heading: 693;
  --weight-body: 400;
  --leading-body: 1.76;
  --leading-heading: 1.24;
  --tracking-heading: -0.008em;
  --radius-sm: 4px;
  --radius-md: 5px;
  --radius-lg: 6px;
  --radius-pill: 6px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 1px 0 rgba(68, 72, 80, 0.12);
  --shadow-2: 0 2px 0 rgba(68, 72, 80, 0.18);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1300px;
  --measure: 73ch;
  --gutter: 24px;
  --section-y: 88px;
  --section-y-lg: 123px;
}

:root {
  --rail-w: 264px;
  --rail-pad-l: 20px;
}

/* ============ reset ============ */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  padding: 0;
  background: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}
p { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; height: auto; }
a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 0.2em; }
button { font: inherit; color: inherit; }
::selection { background: var(--color-highlight); color: var(--color-accent); }
:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* ============ 跳转链接 ============ */
.skip-link {
  position: absolute;
  left: 8px;
  top: -70px;
  z-index: 260;
  padding: 10px 18px;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: 1px dashed var(--color-contrast-accent);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  transition: top 0.18s ease;
}
.skip-link:focus { top: 8px; text-decoration: none; }

/* ============ 阅读进度 ============ */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  z-index: 240;
  transition: width 0.12s linear;
  pointer-events: none;
}

/* ============ 侧栏导览轨道 ============ */
.rail {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--rail-w);
  flex-direction: column;
  gap: var(--space-3);
  padding: var(--space-4) 0 var(--space-3);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-right: 1px solid var(--color-contrast-line);
  overflow-y: auto;
  overscroll-behavior: contain;
  z-index: 120;
}
.rail__head {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 0 var(--space-3) var(--space-2);
  border-bottom: 1px dashed var(--color-contrast-line);
}
.rail__brand { display: flex; flex-direction: column; gap: 3px; color: var(--color-contrast-ink); }
.rail__brand:hover { color: var(--color-contrast-accent); text-decoration: none; }
.rail__brand-cn {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: 1.2;
  letter-spacing: 0.03em;
}
.rail__brand-en {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-contrast-accent);
}
.rail__kicker {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}
.rail__list { display: flex; flex-direction: column; }
.rail__item { display: block; }
.rail__link {
  display: grid;
  grid-template-columns: 30px minmax(0, 1fr);
  align-items: center;
  gap: var(--space-1);
  padding: 9px var(--space-3) 9px var(--rail-pad-l);
  border-left: 2px solid transparent;
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
  font-size: var(--text-sm);
  line-height: 1.4;
  transition: color 0.18s ease, background-color 0.18s ease, border-color 0.18s ease;
}
.rail__link:hover {
  color: var(--color-contrast-ink);
  background: color-mix(in srgb, var(--color-contrast-ink) 7%, transparent);
  text-decoration: none;
}
.rail__link[aria-current="page"] {
  color: var(--color-contrast-ink);
  border-left-color: var(--color-contrast-accent);
  background: color-mix(in srgb, var(--color-contrast-accent) 12%, transparent);
}
.rail__num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 55%, transparent);
}
.rail__link:hover .rail__num,
.rail__link[aria-current="page"] .rail__num { color: var(--color-contrast-accent); }
.rail__text { min-width: 0; }
.rail__foot {
  margin-top: auto;
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: var(--space-2) var(--space-3) 0;
  border-top: 1px dashed var(--color-contrast-line);
}
.rail__desc {
  min-height: 3.2em;
  font-size: var(--text-sm);
  line-height: 1.55;
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
}
.rail__note {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 55%, transparent);
}
.rail__code { color: var(--color-contrast-accent); }

/* ============ 报头 ============ */
.site-header {
  position: relative;
  z-index: 100;
  background: var(--color-surface);
  border-bottom: 1px dashed var(--color-line);
}
.masthead {
  max-width: var(--container);
  margin: 0 auto;
  padding: var(--space-2) var(--gutter) var(--space-3);
}
.masthead__top {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding-bottom: var(--space-2);
  border-bottom: 1px dashed var(--color-line);
}
.masthead__status {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  line-height: 1.5;
  color: var(--color-ink-muted);
}
.status-dot {
  flex: 0 0 auto;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--color-accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-accent) 20%, transparent);
}
.masthead__nameplate {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-top: var(--space-3);
}
.masthead__rule {
  flex: 1 1 0;
  min-width: 20px;
  height: 0;
  border-top: 1px dashed var(--color-line);
}
.brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  flex: 0 1 auto;
  text-align: center;
  color: var(--color-ink);
}
.brand:hover { color: var(--color-primary); text-decoration: none; }
.brand__cn {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-2xl);
  line-height: 1.1;
  letter-spacing: 0.06em;
}
.brand__en {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  color: var(--color-ink-muted);
}
.masthead__tagline {
  margin-top: var(--space-2);
  text-align: center;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: var(--leading-heading);
  color: var(--color-ink);
}
.masthead__meta {
  margin-top: 6px;
  text-align: center;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

/* ============ 主索引导航 ============ */
.site-nav {
  margin-top: var(--space-3);
  border-top: 1px dashed var(--color-line);
  border-bottom: 1px dashed var(--color-line);
}
.site-nav__close { display: none; }
.site-nav__list { display: flex; flex-wrap: wrap; justify-content: center; }
.site-nav__item { min-width: 0; }
.site-nav__item + .site-nav__item { border-left: 1px dotted var(--color-line); }
.site-nav__link {
  display: block;
  padding: 12px 20px;
  font-size: var(--text-sm);
  letter-spacing: 0.02em;
  color: var(--color-ink-soft);
  border-bottom: 2px solid transparent;
  transition: color 0.18s ease, background-color 0.18s ease, border-color 0.18s ease;
}
.site-nav__link:hover {
  color: var(--color-primary);
  background: var(--color-primary-soft);
  text-decoration: none;
}
.site-nav__link[aria-current="page"] {
  color: var(--color-ink);
  font-weight: 600;
  border-bottom-color: var(--color-accent);
}
.site-nav__num {
  display: none;
  margin-right: 10px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-contrast-accent);
}

/* ============ 移动导航按钮 ============ */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 9px 14px;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: 1px solid var(--color-contrast-line);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  cursor: pointer;
}
.nav-toggle:hover { border-color: var(--color-contrast-accent); }
.nav-toggle__bars { display: inline-flex; flex-direction: column; gap: 3px; width: 16px; }
.nav-toggle__bars span { display: block; height: 1px; background: var(--color-contrast-accent); }
.nav-toggle__label { white-space: nowrap; }

/* ============ 桌面端 ============ */
@media (min-width: 1024px) {
  body { padding-left: var(--rail-w); }
  .rail { display: flex; }
  .nav-toggle { display: none; }
  .scroll-progress { left: var(--rail-w); }
  .masthead__top { justify-content: center; }
}

/* ============ 移动抽屉 ============ */
@media (max-width: 1023px) {
  .site-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    margin: 0;
    border: 0;
    padding: calc(var(--space-8) + var(--space-3)) var(--space-3) var(--space-6);
    background: var(--color-contrast-surface);
    color: var(--color-contrast-ink);
    overflow-y: auto;
    overscroll-behavior: contain;
    z-index: 150;
    transform: translateX(-101%);
    visibility: hidden;
    transition: transform 0.26s ease, visibility 0.26s ease;
  }
  .site-nav[data-open] { transform: translateX(0); visibility: visible; }
  .site-nav__close {
    display: inline-flex;
    align-items: center;
    position: absolute;
    top: var(--space-3);
    right: var(--space-3);
    padding: 8px 14px;
    background: transparent;
    color: var(--color-contrast-ink);
    border: 1px dashed var(--color-contrast-line);
    border-radius: var(--radius-md);
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    letter-spacing: 0.1em;
    cursor: pointer;
  }
  .site-nav__close:hover { border-color: var(--color-contrast-accent); color: var(--color-contrast-accent); }
  .site-nav__list {
    flex-direction: column;
    justify-content: flex-start;
    border-top: 1px dashed var(--color-contrast-line);
  }
  .site-nav__item + .site-nav__item { border-left: 0; border-top: 1px dotted var(--color-contrast-line); }
  .site-nav__link {
    padding: 16px 6px;
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    color: var(--color-contrast-ink);
    border-bottom: 0;
  }
  .site-nav__link:hover {
    background: color-mix(in srgb, var(--color-contrast-ink) 8%, transparent);
    color: var(--color-contrast-accent);
  }
  .site-nav__link[aria-current="page"] { color: var(--color-contrast-accent); border-bottom-color: transparent; }
  .site-nav__num { display: inline; }
  html.nav-open { overflow: hidden; }
}

/* ============ 页脚 ============ */
.site-footer {
  margin-top: var(--section-y);
  background: var(--color-surface-alt);
  border-top: 1px dashed var(--color-line);
}
.footer__inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: var(--space-8) var(--gutter) var(--space-4);
}
.footer__brand {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr);
  gap: var(--space-3) var(--space-6);
  align-items: end;
  padding-bottom: var(--space-4);
  border-bottom: 1px dashed var(--color-line);
}
.footer__mark {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-xl);
  letter-spacing: 0.04em;
  color: var(--color-ink);
}
.footer__mark:hover { color: var(--color-primary); text-decoration: none; }
.footer__lede {
  margin-top: 8px;
  max-width: 48ch;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-ink-soft);
}
.footer__stamp {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.9;
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  text-align: right;
}
.footer__stamp-sep { color: var(--color-accent); }
.footer__grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-4) var(--space-6);
  padding: var(--space-6) 0;
}
.footer__col { min-width: 0; }
.footer__heading {
  margin-bottom: var(--space-2);
  padding-bottom: 10px;
  border-bottom: 1px dotted var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-heading);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}
.footer__list { display: flex; flex-direction: column; gap: 10px; }
.footer__list a { font-size: var(--text-sm); color: var(--color-ink-soft); }
.footer__list a:hover { color: var(--color-primary); }
.footer__list span { font-size: var(--text-sm); line-height: 1.6; color: var(--color-ink-soft); }
.footer__list--mono span {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  word-break: break-word;
}
.footer__bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--space-2) var(--space-6);
  padding-top: var(--space-3);
  border-top: 1px dashed var(--color-line);
}
.footer__legal {
  max-width: 68ch;
  font-size: var(--text-xs);
  line-height: 1.8;
  color: var(--color-ink-muted);
}
.footer__copy {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
  white-space: nowrap;
}
@media (max-width: 900px) {
  .footer__grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer__brand { grid-template-columns: minmax(0, 1fr); align-items: start; }
  .footer__stamp { text-align: left; }
}
@media (max-width: 520px) {
  .footer__grid { grid-template-columns: minmax(0, 1fr); }
}

/* ============ 通用容器与栅格 ============ */
.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding-left: var(--gutter);
  padding-right: var(--gutter);
}
.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}
@media (max-width: 900px) {
  .grid-12 { grid-template-columns: repeat(6, minmax(0, 1fr)); }
}
@media (max-width: 600px) {
  .grid-12 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
.prose { max-width: var(--measure); }
.prose p + p { margin-top: var(--space-2); }
.rule-dots { height: 0; margin: var(--space-3) 0; border: 0; border-top: 1px dotted var(--color-line); }

/* ============ 面包屑 ============ */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  padding: var(--space-3) 0 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}
.breadcrumb a { color: var(--color-ink-soft); }
.breadcrumb a:hover { color: var(--color-primary); }
.breadcrumb__sep { color: var(--color-line); }

/* ============ 章节抬头 ============ */
.section-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: var(--space-2);
  align-items: baseline;
  padding-top: var(--space-3);
  border-top: 1px dashed var(--color-line);
}
.index-num {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  color: var(--color-accent);
}

/* ============ 按钮 ============ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 12px 22px;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 600;
  line-height: 1.2;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}
.btn:hover { text-decoration: none; }
.btn--primary { background: var(--color-accent); color: var(--color-accent-ink); border-color: var(--color-accent); }
.btn--primary:hover { background: var(--color-focus); border-color: var(--color-focus); color: var(--color-accent-ink); }
.btn--ghost { background: transparent; color: var(--color-ink); border: 1px dashed var(--color-line); }
.btn--ghost:hover { background: var(--color-primary-soft); border-color: var(--color-primary); color: var(--color-primary); }
.btn--ink { background: var(--color-contrast-surface); color: var(--color-contrast-ink); border-color: var(--color-contrast-line); }
.btn--ink:hover { background: color-mix(in srgb, var(--color-contrast-accent) 22%, var(--color-contrast-surface)); color: var(--color-contrast-ink); }

/* ============ 状态标签 ============ */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 9px;
  border: 1px dashed color-mix(in srgb, var(--color-accent) 42%, transparent);
  border-radius: var(--radius-sm);
  background: var(--color-highlight);
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  line-height: 1.4;
}
.tag--region {
  background: var(--color-primary-soft);
  color: var(--color-primary);
  border-color: color-mix(in srgb, var(--color-primary) 40%, transparent);
}

/* ============ 图片容器 ============ */
.media-frame {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-lg);
  background: var(--color-surface-deep);
}
.media-frame__img { width: 100%; height: 100%; object-fit: cover; border-radius: calc(var(--radius-lg) - 1px); }
.media-frame__scrim { position: absolute; inset: 0; background: var(--overlay-scrim); pointer-events: none; }
.media-frame__caption {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  padding: var(--space-3);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.6;
  letter-spacing: 0.06em;
}
.media-frame--wide { aspect-ratio: 16 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--square { aspect-ratio: 1 / 1; }

/* ============ 滚动显现 ============ */
.js [data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.32s ease-out, transform 0.32s ease-out;
}
.js [data-reveal].is-visible { opacity: 1; transform: none; }

/* ============ 降级动效 ============ */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
  .js [data-reveal] { opacity: 1; transform: none; }
  .scroll-progress { transition: none; }
  .site-nav { transition: none; }
  html { scroll-behavior: auto; }
}

html { scroll-behavior: smooth; }