:root {
  --color-surface: #f0efef;
  --color-surface-alt: #e8e6e6;
  --color-surface-deep: #dddada;
  --color-ink: #4f4041;
  --color-ink-soft: #786365;
  --color-ink-muted: #8b7476;
  --color-line: #d3d0d0;
  --color-primary: #d02f3c;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #ecd4d6;
  --color-accent: #ad610a;
  --color-accent-ink: #ffffff;
  --color-highlight: #e4d5c6;
  --color-focus: #a25701;
  --color-contrast-surface: #2a1819;
  --color-contrast-ink: #e7e4e4;
  --color-contrast-line: #544546;
  --color-contrast-accent: #f1870e;
  --overlay-scrim: linear-gradient(180deg, rgba(42, 24, 25, 0.35) 0%, rgba(42, 24, 25, 0.72) 55%, rgba(42, 24, 25, 0.92) 100%);
  --font-heading: "Songti SC", STSong, "Source Han Serif SC", SimSun, serif;
  --font-body: "Songti SC", STSong, "Source Han Serif SC", SimSun, serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 11.4px;
  --text-sm: 14.3px;
  --text-base: 16px;
  --text-lg: 20.0px;
  --text-xl: 25.0px;
  --text-2xl: 31.2px;
  --text-3xl: 39.1px;
  --text-4xl: 48.8px;
  --text-display: clamp(34px, 7.0vw, 89px);
  --text-figure: clamp(28px, 5.0vw, 64px);
  --weight-heading: 548;
  --weight-body: 400;
  --leading-body: 1.8;
  --leading-heading: 1.17;
  --tracking-heading: 0.027em;
  --radius-sm: 1px;
  --radius-md: 2px;
  --radius-lg: 2px;
  --radius-pill: 2px;
  --border-thin: 1px;
  --border-thick: 2px;
  --shadow-1: none;
  --shadow-2: none;
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1140px;
  --measure: 68ch;
  --gutter: 24px;
  --section-y: 99px;
  --section-y-lg: 139px;
}

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

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

body {
  margin: 0;
  background-color: 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);
  letter-spacing: 0.01em;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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);
}

p { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
a { color: inherit; }
button { font: inherit; color: inherit; }
hr { border: 0; margin: 0; }
figure { margin: 0; }
time, .mono, .marker, .meta { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }
strong, b { font-weight: var(--weight-heading); }
::selection { background-color: var(--color-primary-soft); color: var(--color-ink); }

:focus-visible {
  outline: var(--border-thick) solid var(--color-focus);
  outline-offset: 2px;
}

/* ============================================================
   2. 版面骨架
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

#main-content { padding-top: 79px; display: block; }
#main-content > .bleed-top { margin-top: -79px; }

.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--alt { background-color: var(--color-surface-alt); }
.section--deep { background-color: var(--color-surface-deep); }
.section--dark {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.section--dark .section-head__lead { color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent); }
.section--dark .rule-double { border-top-color: var(--color-contrast-line); }
.section--dark .eyebrow::before,
.section--dark .eyebrow::after { background-color: var(--color-contrast-accent); }
.section--dark .meta { color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent); }

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}
.span-3 { grid-column: span 3; }
.span-4 { grid-column: span 4; }
.span-5 { grid-column: span 5; }
.span-6 { grid-column: span 6; }
.span-7 { grid-column: span 7; }
.span-8 { grid-column: span 8; }
.span-12 { grid-column: span 12; }

.measure { max-width: var(--measure); }
.center { text-align: center; margin-inline: auto; }
.stack > * + * { margin-top: var(--space-2); }
.meta {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  letter-spacing: 0.06em;
  line-height: 1.6;
}

/* ============================================================
   3. 章节头与中式分隔语言
   ============================================================ */
.eyebrow {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
  margin-bottom: var(--space-2);
}
.eyebrow::before,
.eyebrow::after {
  content: "";
  display: block;
  width: 34px;
  height: 1px;
  background-color: var(--color-primary);
}
.eyebrow--left { justify-content: flex-start; }
.eyebrow--left::after { display: none; }

.section-head {
  text-align: center;
  max-width: 44rem;
  margin: 0 auto var(--space-6);
}
.section-head__title {
  font-size: var(--text-2xl);
  letter-spacing: 0.06em;
}
.section-head__lead {
  margin-top: var(--space-2);
  color: var(--color-ink-soft);
  font-size: var(--text-base);
}

.rule-double {
  height: 0;
  border-top: 3px double var(--color-line);
}
.rule-fret {
  height: 9px;
  background-image:
    repeating-linear-gradient(90deg, var(--color-line) 0 1px, transparent 1px 9px),
    repeating-linear-gradient(0deg, var(--color-line) 0 1px, transparent 1px 9px);
  background-size: 9px 9px;
  opacity: 0.9;
}

.fret-box {
  position: relative;
  padding: var(--space-3);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background-color: var(--color-surface);
}
.fret-box::after {
  content: "";
  position: absolute;
  inset: 4px;
  border: 3px double var(--color-line);
  border-radius: var(--radius-sm);
  pointer-events: none;
}
.fret-box--highlight { background-color: var(--color-highlight); }
.fret-box--dark {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-color: var(--color-contrast-line);
}
.fret-box--dark::after { border-color: var(--color-contrast-line); }

.fret-corners {
  background-image:
    linear-gradient(var(--color-accent), var(--color-accent)),
    linear-gradient(var(--color-accent), var(--color-accent)),
    linear-gradient(var(--color-accent), var(--color-accent)),
    linear-gradient(var(--color-accent), var(--color-accent)),
    linear-gradient(var(--color-accent), var(--color-accent)),
    linear-gradient(var(--color-accent), var(--color-accent)),
    linear-gradient(var(--color-accent), var(--color-accent)),
    linear-gradient(var(--color-accent), var(--color-accent));
  background-repeat: no-repeat;
  background-size: 10px 1px, 1px 10px, 10px 1px, 1px 10px, 10px 1px, 1px 10px, 10px 1px, 1px 10px;
  background-position: left top, left top, right top, right top, left bottom, left bottom, right bottom, right bottom;
}

.marker {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 22px;
  height: 22px;
  padding-inline: 5px;
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-xs);
  line-height: 1;
  border-radius: var(--radius-sm);
  letter-spacing: 0.04em;
}
.marker--accent { background-color: var(--color-accent); color: var(--color-accent-ink); }
.section--dark .marker--accent,
.fret-box--dark .marker--accent { background-color: var(--color-contrast-accent); color: var(--color-contrast-surface); }

/* ============================================================
   4. 按钮
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 10px 22px;
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-sm);
  background-color: transparent;
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  text-decoration: none;
  cursor: pointer;
  transition: border-color 0.2s ease, color 0.2s ease, background-color 0.2s ease;
}
.btn:hover {
  border-color: var(--color-primary);
  border-style: double;
  border-width: 3px;
  padding: 8px 20px;
  color: var(--color-primary);
}
.btn--primary {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.btn--primary:hover {
  background-color: color-mix(in srgb, var(--color-primary) 84%, var(--color-contrast-surface));
  border-color: color-mix(in srgb, var(--color-primary) 84%, var(--color-contrast-surface));
  color: var(--color-primary-ink);
  padding: 8px 20px;
}
.btn--dark {
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}
.btn--dark:hover {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

/* ============================================================
   5. 图片容器
   ============================================================ */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background-color: var(--color-surface-deep);
}
.media-frame__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: var(--radius-md);
}
.media-frame__scrim {
  position: absolute;
  inset: 0;
  background-image: 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-size: var(--text-sm);
  line-height: 1.6;
}
.media-frame__caption .meta { color: color-mix(in srgb, var(--color-contrast-ink) 70%, transparent); }
.media-frame--wide { aspect-ratio: 16 / 9; }
.media-frame--photo { aspect-ratio: 4 / 3; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--tall { aspect-ratio: 3 / 4; }

/* ============================================================
   6. 横向右滑带
   ============================================================ */
.rail {
  display: flex;
  gap: var(--space-3);
  overflow-x: auto;
  overscroll-behavior-x: contain;
  scroll-snap-type: x mandatory;
  padding-bottom: var(--space-2);
  scrollbar-width: thin;
  scrollbar-color: var(--color-line) transparent;
}
.rail > .rail__item {
  flex: 0 0 auto;
  scroll-snap-align: start;
  width: min(300px, 76vw);
}
.rail::-webkit-scrollbar { height: 6px; }
.rail::-webkit-scrollbar-track { background: transparent; }
.rail::-webkit-scrollbar-thumb { background-color: var(--color-line); border-radius: var(--radius-sm); }
.rail:focus-visible { outline: var(--border-thick) solid var(--color-focus); outline-offset: 4px; }

/* ============================================================
   7. 显现动效
   ============================================================ */
.js-reveal [data-reveal] {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}
.js-reveal [data-reveal].is-in {
  opacity: 1;
  transform: none;
}

/* ============================================================
   8. 顶栏
   ============================================================ */
.skip-link {
  position: absolute;
  top: -120px;
  left: var(--space-2);
  z-index: 120;
  padding: 10px 18px;
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: var(--border-thin) solid var(--color-contrast-accent);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  text-decoration: none;
}
.skip-link:focus { top: var(--space-2); }

.site-header {
  --nav-accent: var(--color-contrast-accent);
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 80;
  color: var(--color-contrast-ink);
  background-color: transparent;
  background-image: linear-gradient(
    180deg,
    color-mix(in srgb, var(--color-contrast-surface) 80%, transparent) 0%,
    color-mix(in srgb, var(--color-contrast-surface) 36%, transparent) 60%,
    color-mix(in srgb, var(--color-contrast-surface) 0%, transparent) 100%
  );
  border-bottom: 3px double transparent;
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}
.site-header[data-scrolled],
.site-header[data-menu="open"] {
  --nav-accent: var(--color-primary);
  background-color: var(--color-surface);
  background-image: none;
  color: var(--color-ink);
  border-bottom-color: var(--color-line);
}

.header-inner {
  width: 100%;
  max-width: var(--container);
  min-height: 76px;
  margin-inline: auto;
  padding: 10px var(--gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: inherit;
  flex: 0 1 auto;
  min-width: 0;
}
.brand-mark {
  flex: 0 0 auto;
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  border: 3px double currentColor;
  border-radius: var(--radius-sm);
  color: var(--nav-accent);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1;
  transition: color 0.3s ease;
}
.brand-text { display: flex; flex-direction: column; min-width: 0; }
.brand-name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: 0.14em;
  line-height: 1.25;
}
.brand-tag {
  margin-top: 2px;
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  opacity: 0.72;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  background-color: transparent;
  border: var(--border-thin) solid var(--nav-accent);
  border-radius: var(--radius-sm);
  color: var(--nav-accent);
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  cursor: pointer;
}
.nav-toggle-bars {
  position: relative;
  display: block;
  width: 16px;
  height: 10px;
}
.nav-toggle-bars::before,
.nav-toggle-bars::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 1px;
  background-color: currentColor;
  transition: transform 0.22s ease, top 0.22s ease, bottom 0.22s ease;
}
.nav-toggle-bars::before { top: 1px; }
.nav-toggle-bars::after { bottom: 1px; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::before {
  top: 50%;
  transform: translateY(-50%) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::after {
  bottom: 50%;
  transform: translateY(50%) rotate(-45deg);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
}
.nav-link {
  position: relative;
  display: block;
  padding: 6px 10px;
  color: inherit;
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  text-decoration: none;
  white-space: nowrap;
  transition: color 0.2s ease;
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 50%;
  right: 50%;
  bottom: 0;
  height: 2px;
  background-color: var(--nav-accent);
  transition: left 0.22s ease, right 0.22s ease;
}
.nav-link:hover::after,
.nav-link:focus-visible::after { left: 10px; right: 10px; }
.nav-link[aria-current="page"] { color: var(--nav-accent); }
.nav-link[aria-current="page"]::after { left: 10px; right: 10px; }

.nav-cta {
  display: inline-block;
  padding: 7px 15px;
  border: var(--border-thin) solid var(--nav-accent);
  border-radius: var(--radius-sm);
  color: var(--nav-accent);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  text-decoration: none;
  white-space: nowrap;
  transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}
.nav-cta:hover {
  background-color: color-mix(in srgb, var(--nav-accent) 16%, transparent);
  border-style: double;
  border-width: 3px;
  padding: 5px 13px;
}

/* ============================================================
   9. 页脚
   ============================================================ */
.site-footer {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: 3px double var(--color-contrast-line);
  margin-top: var(--section-y);
}
.footer-inner {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-4) var(--gutter);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2) var(--space-3);
  font-size: var(--text-sm);
}
.footer-brand {
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  letter-spacing: 0.1em;
}
.footer-nav { display: flex; flex-wrap: wrap; gap: var(--space-3); }
.footer-nav a {
  color: inherit;
  text-decoration: none;
  opacity: 0.82;
  border-bottom: var(--border-thin) solid transparent;
  transition: opacity 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}
.footer-nav a:hover {
  opacity: 1;
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}
.footer-meta {
  color: color-mix(in srgb, var(--color-contrast-ink) 76%, transparent);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
}
.footer-legal {
  flex: 1 0 100%;
  padding-top: var(--space-2);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
}
.footer-sep {
  display: inline-block;
  margin-inline: 0.4em;
  color: color-mix(in srgb, var(--color-contrast-ink) 42%, transparent);
}

/* ============================================================
   10. 响应式
   ============================================================ */
@media (max-width: 1024px) {
  .span-3, .span-4, .span-5 { grid-column: span 6; }
  .span-7, .span-8 { grid-column: span 12; }
  :root { --section-y: 80px; --section-y-lg: 104px; }
}

@media (max-width: 900px) {
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: fixed;
    top: 79px;
    left: 0;
    right: 0;
    display: block;
    max-height: calc(100vh - 79px);
    overflow-y: auto;
    padding: var(--space-2) var(--gutter) var(--space-4);
    background-color: var(--color-surface);
    color: var(--color-ink);
    --nav-accent: var(--color-primary);
    border-bottom: 3px double var(--color-line);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: opacity 0.24s ease, transform 0.24s ease, visibility 0.24s;
  }
  .site-nav[data-open] {
    opacity: 1;
    visibility: visible;
    transform: none;
  }
  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }
  .nav-list > li + li { border-top: var(--border-thin) solid var(--color-line); }
  .nav-link { padding: 14px 2px; font-size: var(--text-base); }
  .nav-link::after { display: none; }
  .nav-link[aria-current="page"] {
    color: var(--color-primary);
    border-left: 3px double var(--color-primary);
    padding-left: 12px;
    margin-left: -2px;
  }
  .nav-cta {
    display: block;
    margin-top: var(--space-3);
    padding: 12px;
    text-align: center;
  }
  .nav-cta:hover { padding: 10px; }

  .brand-mark { width: 32px; height: 32px; font-size: var(--text-base); }
  .brand-name { font-size: var(--text-base); letter-spacing: 0.1em; }
  .brand-tag { display: none; }

  .footer-inner { flex-direction: column; align-items: flex-start; }
  .footer-legal { padding-top: var(--space-3); }
}

@media (max-width: 720px) {
  .grid { grid-template-columns: repeat(6, minmax(0, 1fr)); }
  .span-3, .span-4, .span-5, .span-6, .span-7, .span-8 { grid-column: span 6; }
  .section-head__title { font-size: var(--text-xl); }
  .rail > .rail__item { width: 82vw; }
  :root { --section-y: 64px; --section-y-lg: 80px; }
}

@media (max-width: 420px) {
  .header-inner { padding-inline: var(--space-2); }
  .container { padding-inline: var(--space-2); }
}

/* ============================================================
   11. 动效偏好
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .js-reveal [data-reveal] { opacity: 1; transform: none; }
  .rail { scroll-snap-type: none; }
}

@media print {
  .site-header, .skip-link, .rail { display: none; }
  #main-content { padding-top: 0; }
  body { background: #fff; }
}