:root {
  --color-surface: #fafafa;
  --color-surface-alt: #f1f1f1;
  --color-surface-deep: #e5e5e4;
  --color-ink: #4d4842;
  --color-ink-soft: #736c64;
  --color-ink-muted: #878178;
  --color-line: #dbdad9;
  --color-primary: #9d6b25;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #ede6dc;
  --color-accent: #0f77c7;
  --color-accent-ink: #ffffff;
  --color-highlight: #d0e2f1;
  --color-focus: #0472c8;
  --color-contrast-surface: #2b2318;
  --color-contrast-ink: #e7e6e4;
  --color-contrast-line: #544e45;
  --color-contrast-accent: #1790ed;
  --overlay-scrim: linear-gradient(180deg, rgba(43, 35, 24, 0.35) 0%, rgba(43, 35, 24, 0.72) 55%, rgba(43, 35, 24, 0.92) 100%);
  --font-heading: "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --text-xs: 10.7px;
  --text-sm: 13.4px;
  --text-base: 15px;
  --text-lg: 18.8px;
  --text-xl: 23.4px;
  --text-2xl: 29.3px;
  --text-3xl: 36.6px;
  --text-4xl: 45.8px;
  --text-display: clamp(34px, 5.9vw, 75px);
  --text-figure: clamp(28px, 4.2vw, 54px);
  --weight-heading: 631;
  --weight-body: 400;
  --leading-body: 1.68;
  --leading-heading: 1.2;
  --tracking-heading: 0.007em;
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --radius-pill: 999px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 1px 0 rgba(77, 72, 66, 0.12);
  --shadow-2: 0 2px 0 rgba(77, 72, 66, 0.18);
  --space-1: 7px;
  --space-2: 14px;
  --space-3: 21px;
  --space-4: 28px;
  --space-6: 42px;
  --space-8: 56px;
  --container: 1340px;
  --measure: 74ch;
  --gutter: 28px;
  --section-y: 64px;
  --section-y-lg: 90px;
}

/* ==========================================================================
   1. Reset
   ========================================================================== */

*,
*::before,
*::after { box-sizing: border-box; }

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

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);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd, ol, ul, pre { margin: 0; }
ol, ul { padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
img { height: auto; }
button, input, select, textarea { font: inherit; color: inherit; }
button { cursor: pointer; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; width: 100%; }
summary { list-style: none; }
summary::-webkit-details-marker { display: none; }

/* ==========================================================================
   2. 中文排版与数字
   ========================================================================== */

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
  text-wrap: balance;
}

p { text-wrap: pretty; }

.num,
time,
[data-num],
code,
kbd,
samp,
.card__index,
.figure,
.figure__unit,
.tag,
.chip,
.filter-btn,
.footer-hero__kicker,
.footer-contact__label,
.section-head__num,
.breadcrumb,
.nav-toggle__text {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1;
}

/* ==========================================================================
   3. 无障碍
   ========================================================================== */

.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;
}

.skip-link {
  position: absolute;
  left: var(--space-2);
  top: -120px;
  z-index: 300;
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  transition: top 0.16s ease;
}

.skip-link:focus { top: var(--space-1); }

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

/* ==========================================================================
   4. 布局基础
   ========================================================================== */

.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.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-contrast-surface);
  color: var(--color-contrast-ink);
}
.section--deep h1,
.section--deep h2,
.section--deep h3,
.section--deep h4 { color: var(--color-contrast-ink); }
.section--deep p,
.section--deep li {
  color: color-mix(in srgb, var(--color-contrast-ink) 82%, var(--color-contrast-surface));
}

.grid {
  display: grid;
  gap: var(--gutter);
}
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

.card-grid {
  display: grid;
  gap: var(--gutter);
  grid-template-columns: repeat(auto-fill, minmax(268px, 1fr));
}
.card-grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.card-grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.card-grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

/* ==========================================================================
   5. 章节头 / 超大编号
   ========================================================================== */

.section-head {
  display: grid;
  gap: var(--space-2);
  margin-bottom: var(--space-6);
}

.section-head__num {
  font-size: var(--text-4xl);
  line-height: 1;
  font-weight: var(--weight-heading);
  letter-spacing: 0.02em;
  color: var(--color-primary);
}

.section-head__title {
  font-size: var(--text-2xl);
  margin: 0;
}

.section-head__lead {
  max-width: var(--measure);
  font-size: var(--text-base);
  color: var(--color-ink-soft);
}

.section--deep .section-head__num { color: var(--color-contrast-accent); }
.section--deep .section-head__lead {
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, var(--color-contrast-surface));
}

/* ==========================================================================
   6. 页头
   ========================================================================== */

.site-header {
  background-color: var(--color-surface);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.header-top {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.header-top__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  min-height: 46px;
  padding-block: var(--space-1);
}

.brand {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-2);
  min-width: 0;
}

.brand__mark {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
  white-space: nowrap;
  border-bottom: 2px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}

.brand__mark:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

.brand__tagline {
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, var(--color-contrast-surface));
}

.header-top__side {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-xs);
}

.header-top__label {
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, var(--color-contrast-surface));
  white-space: nowrap;
}

.header-top__link {
  color: var(--color-contrast-accent);
  border-bottom: 1px solid transparent;
  transition: border-color 0.18s ease, color 0.18s ease;
  word-break: break-all;
}

.header-top__link:hover { border-bottom-color: var(--color-contrast-accent); }

.header-main { background-color: var(--color-surface); }

.header-main__inner {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-height: 54px;
}

.site-nav { flex: 1 1 auto; min-width: 0; }

.site-nav__list {
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
}

.site-nav__link {
  position: relative;
  display: flex;
  align-items: center;
  padding: 15px var(--space-3);
  font-size: var(--text-sm);
  color: var(--color-ink);
  white-space: nowrap;
  transition: color 0.18s ease;
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: var(--space-3);
  right: var(--space-3);
  bottom: 8px;
  height: 2px;
  background-color: var(--color-accent);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.22s ease, background-color 0.22s ease;
}

.site-nav__link:hover { color: var(--color-accent); }
.site-nav__link:hover::after {
  transform: scaleX(1);
  background-color: color-mix(in srgb, var(--color-accent) 42%, var(--color-surface));
}

.site-nav__link[aria-current="page"] { color: var(--color-accent); }
.site-nav__link[aria-current="page"]::after {
  transform: scaleX(1);
  background-color: var(--color-accent);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 9px 13px;
  min-height: 40px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface);
  color: var(--color-ink);
  font-size: var(--text-sm);
  transition: border-color 0.18s ease, color 0.18s ease, background-color 0.18s ease;
}

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

.nav-toggle__icon {
  display: inline-flex;
  flex-direction: column;
  justify-content: space-between;
  width: 16px;
  height: 12px;
}

.nav-toggle__icon span {
  display: block;
  height: 2px;
  border-radius: 1px;
  background-color: currentColor;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__icon span:nth-child(1) {
  transform: translateY(5px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__icon span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__icon span:nth-child(3) {
  transform: translateY(-5px) rotate(-45deg);
}

.nav-toggle__text { font-size: var(--text-xs); }

/* ==========================================================================
   7. 页脚
   ========================================================================== */

.site-footer {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.footer-hero {
  padding-block: var(--section-y-lg) var(--space-6);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.footer-hero__kicker {
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-contrast-accent);
  margin-bottom: var(--space-3);
}

.footer-hero__big {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-display);
  line-height: 1.05;
  letter-spacing: -0.004em;
  color: var(--color-contrast-ink);
}

.footer-body { padding-block: var(--space-8); }

.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-6) var(--space-4);
}

.footer-col__title {
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
  padding-bottom: var(--space-1);
  margin-bottom: var(--space-2);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.footer-col__list {
  display: grid;
  gap: 9px;
}

.footer-col__list a {
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, var(--color-contrast-surface));
  border-bottom: 1px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
  justify-self: start;
}

.footer-col__list a:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

.footer-col__note {
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 68%, var(--color-contrast-surface));
}

.footer-col__note + .footer-col__note { margin-top: var(--space-2); }

.footer-contact {
  display: grid;
  gap: var(--space-2);
}

.footer-contact li {
  display: grid;
  gap: 2px;
}

.footer-contact__label {
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 52%, var(--color-contrast-surface));
}

.footer-contact__value {
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
  word-break: break-word;
}

.footer-base {
  padding-block: var(--space-3);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.footer-base__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
}

.footer-base__copy,
.footer-legal {
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, var(--color-contrast-surface));
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.footer-legal a {
  border-bottom: 1px solid var(--color-contrast-line);
  transition: color 0.18s ease, border-color 0.18s ease;
}

.footer-legal a:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

/* ==========================================================================
   8. 按钮
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 11px 20px;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  line-height: 1.2;
  text-align: center;
  transition: background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease,
              transform 0.18s ease, box-shadow 0.18s ease;
}

.btn:hover { text-decoration: none; }
.btn:active { transform: translateY(1px); }

.btn--primary {
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  box-shadow: var(--shadow-1);
}
.btn--primary:hover {
  background-color: color-mix(in srgb, var(--color-primary) 86%, var(--color-contrast-surface));
  transform: translateY(-1px);
  box-shadow: var(--shadow-2);
}

.btn--accent {
  background-color: var(--color-accent);
  color: var(--color-accent-ink);
  box-shadow: var(--shadow-1);
}
.btn--accent:hover {
  background-color: color-mix(in srgb, var(--color-accent) 86%, var(--color-contrast-surface));
  transform: translateY(-1px);
  box-shadow: var(--shadow-2);
}

.btn--ghost {
  background-color: transparent;
  border-color: var(--color-line);
  color: var(--color-ink);
}
.btn--ghost:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.btn--on-dark {
  background-color: transparent;
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}
.btn--on-dark:hover {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

/* ==========================================================================
   9. 面包屑
   ========================================================================== */

.breadcrumb {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
}

.breadcrumb__list li {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.breadcrumb__list li + li::before {
  content: "/";
  color: var(--color-line);
}

.breadcrumb a {
  color: var(--color-ink-soft);
  border-bottom: 1px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}

.breadcrumb a:hover {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.breadcrumb [aria-current="page"] { color: var(--color-ink); }

/* ==========================================================================
   10. 资料卡
   ========================================================================== */

.card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  padding: var(--space-3);
  background-color: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-1);
  transition: border-color 0.18s ease, transform 0.18s ease, box-shadow 0.18s ease;
}

.card:hover {
  border-color: var(--color-accent);
  transform: translateY(-1px);
  box-shadow: var(--shadow-2);
}

.card--flat { box-shadow: none; }
.card--soft { background-color: var(--color-primary-soft); border-color: color-mix(in srgb, var(--color-primary) 30%, var(--color-line)); }

.card__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-2);
}

.card__index {
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.card__title {
  font-size: var(--text-lg);
  line-height: 1.32;
}

.card__text {
  font-size: var(--text-sm);
  line-height: 1.72;
  color: var(--color-ink-soft);
}

.card__meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-2);
  margin-top: auto;
  padding-top: var(--space-2);
  border-top: var(--border-thin) solid var(--color-line);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
}

.section--deep .card {
  background-color: color-mix(in srgb, var(--color-contrast-surface) 88%, var(--color-contrast-ink));
  border-color: var(--color-contrast-line);
  box-shadow: none;
}
.section--deep .card:hover { border-color: var(--color-contrast-accent); box-shadow: none; }
.section--deep .card__title { color: var(--color-contrast-ink); }
.section--deep .card__text { color: color-mix(in srgb, var(--color-contrast-ink) 72%, var(--color-contrast-surface)); }
.section--deep .card__meta { border-top-color: var(--color-contrast-line); color: color-mix(in srgb, var(--color-contrast-ink) 55%, var(--color-contrast-surface)); }

/* ==========================================================================
   11. 分类色标与标签
   ========================================================================== */

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
  white-space: nowrap;
}

.tag::before {
  content: "";
  flex: none;
  width: 8px;
  height: 8px;
  border-radius: 2px;
  background-color: var(--color-ink-muted);
  box-sizing: border-box;
}

.tag--hit::before { background-color: var(--color-primary); }
.tag--miss::before {
  background-color: transparent;
  border: 1.5px solid var(--color-accent);
}
.tag--replay::before {
  background-color: transparent;
  background-image: repeating-linear-gradient(
    45deg,
    var(--color-ink-muted) 0 2px,
    transparent 2px 4px
  );
  border: 1.5px solid var(--color-line);
  border-radius: 1px;
}
.tag--pending::before {
  background-color: transparent;
  border: 1.5px solid var(--color-line);
}

.section--deep .tag { color: color-mix(in srgb, var(--color-contrast-ink) 72%, var(--color-contrast-surface)); }
.section--deep .tag--hit::before { background-color: var(--color-primary-soft); }
.section--deep .tag--miss::before { border-color: var(--color-contrast-accent); }
.section--deep .tag--replay::before,
.section--deep .tag--pending::before { border-color: var(--color-contrast-line); }

.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  background-color: var(--color-surface);
  font-size: var(--text-xs);
  color: var(--color-ink-soft);
}

.chip--active {
  background-color: var(--color-highlight);
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ==========================================================================
   12. 数字与面板
   ========================================================================== */

.figure {
  display: inline-flex;
  align-items: baseline;
  gap: 4px;
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 1;
  color: var(--color-ink);
}

.figure--primary { color: var(--color-primary); }
.figure--accent { color: var(--color-accent); }
.figure--on-dark { color: var(--color-contrast-accent); }

.figure__unit {
  font-size: var(--text-sm);
  font-weight: var(--weight-body);
  color: var(--color-ink-muted);
}

.section--deep .figure__unit { color: color-mix(in srgb, var(--color-contrast-ink) 60%, var(--color-contrast-surface)); }

.figure-panel {
  display: grid;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-4);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-md);
  border: var(--border-thin) solid var(--color-contrast-line);
}

.figure-panel__label {
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, var(--color-contrast-surface));
  font-family: var(--font-mono);
}

.stat {
  display: grid;
  gap: var(--space-1);
}

.stat__label {
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  color: var(--color-ink-muted);
}

/* ==========================================================================
   13. 图像容器
   ========================================================================== */

.media {
  position: relative;
  display: block;
  overflow: hidden;
  width: 100%;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background-color: var(--color-surface-deep);
}

.media > img,
.media > svg {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media--4x3 { aspect-ratio: 4 / 3; }
.media--16x9 { aspect-ratio: 16 / 9; }
.media--1x1 { aspect-ratio: 1 / 1; }
.media--21x9 { aspect-ratio: 21 / 9; }

.media__caption {
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  padding: var(--space-2) var(--space-3);
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
  font-size: var(--text-xs);
  line-height: 1.6;
}

.media-frame {
  padding: var(--space-2);
  background-color: var(--color-surface-deep);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
}

.media-frame .media {
  border-radius: var(--radius-sm);
  border-color: color-mix(in srgb, var(--color-line) 60%, var(--color-ink-muted));
}

.section--deep .media-frame {
  background-color: color-mix(in srgb, var(--color-contrast-surface) 84%, var(--color-contrast-ink));
  border-color: var(--color-contrast-line);
}
.section--deep .media { border-color: var(--color-contrast-line); }

/* ==========================================================================
   14. 筛选与折叠
   ========================================================================== */

.filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2);
  background-color: var(--color-surface-deep);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
}

.filter-btn {
  appearance: none;
  padding: 6px 14px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  background-color: var(--color-surface);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
  transition: background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease;
}

.filter-btn:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.filter-btn[aria-pressed="true"] {
  background-color: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-accent-ink);
}

.filter-status {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

[data-filter-item][hidden] { display: none; }

.fold {
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background-color: var(--color-surface);
  overflow: hidden;
}

.fold + .fold { margin-top: -1px; }

.fold summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
  transition: background-color 0.18s ease, color 0.18s ease;
}

.fold summary::after {
  content: "+";
  font-family: var(--font-mono);
  color: var(--color-ink-muted);
}

.fold[open] summary::after { content: "–"; }
.fold summary:hover { color: var(--color-accent); }
.fold__body {
  padding: 0 var(--space-3) var(--space-3);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

/* ==========================================================================
   15. 文本工具
   ========================================================================== */

.lede {
  max-width: var(--measure);
  font-size: var(--text-lg);
  line-height: 1.6;
  color: var(--color-ink-soft);
}

.prose {
  max-width: var(--measure);
  font-size: var(--text-base);
}

.prose p + p { margin-top: var(--space-2); }
.prose a {
  color: var(--color-accent);
  border-bottom: 1px solid color-mix(in srgb, var(--color-accent) 40%, transparent);
}
.prose a:hover { border-bottom-color: var(--color-accent); }

.note {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

.rule {
  height: var(--border-thin);
  background-color: var(--color-line);
  border: 0;
}

/* ==========================================================================
   16. 响应式
   ========================================================================== */

@media (max-width: 1080px) {
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .card-grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

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

  .section { padding-block: var(--space-8); }
  .section--lg { padding-block: var(--section-y); }
  .footer-hero { padding-block: var(--section-y) var(--space-6); }

  .header-main__inner {
    flex-wrap: wrap;
    padding-block: var(--space-1);
    min-height: 0;
  }

  .nav-toggle {
    display: inline-flex;
    margin-left: auto;
  }

  .site-nav {
    display: none;
    flex-basis: 100%;
  }

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

  .site-nav__list {
    flex-direction: column;
    width: 100%;
    padding-bottom: var(--space-1);
  }

  .site-nav__list > li { width: 100%; }

  .site-nav__link {
    width: 100%;
    padding: 13px 0;
    border-bottom: var(--border-thin) solid var(--color-line);
  }

  .site-nav__link::after {
    left: 0;
    right: auto;
    width: 30px;
    bottom: 6px;
  }

  .footer-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: var(--space-4) var(--space-3);
  }
}

@media (max-width: 640px) {
  .container { padding-inline: var(--space-2); }

  .grid--2,
  .grid--3,
  .grid--4,
  .card-grid--2,
  .card-grid--3,
  .card-grid--4 {
    grid-template-columns: minmax(0, 1fr);
  }

  .header-top__inner {
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
    padding-block: var(--space-1);
  }

  .header-top__side { flex-wrap: wrap; }

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

  .footer-base__inner { flex-direction: column; align-items: flex-start; }

  .filter-status { margin-left: 0; }
}

@media (max-width: 420px) {
  .brand { gap: 4px; }
  .site-nav__link { font-size: var(--text-sm); }
}

/* ==========================================================================
   17. 减弱动效
   ========================================================================== */

@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;
    transition-delay: 0ms !important;
  }

  .card:hover,
  .btn:hover { transform: none; }
}