/* ============================================================
   万利平台 · 共享样式表 /assets/site.css
   刊头 + 页脚 + 基础组件
   ============================================================ */

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

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

body,
h1, h2, h3, h4, h5, p, ul, ol, li, figure, blockquote, dl, dd { margin: 0; padding: 0; }

ul, ol { list-style: none; }

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

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

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

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

:focus-visible {
  outline: 2px solid var(--cyan-400);
  outline-offset: 3px;
  border-radius: 1px;
}

/* ---------- 2. 设计令牌 ---------- */
:root {
  --indigo-950: #0B1230;
  --indigo-800: #16224F;
  --indigo-600: #24356F;
  --sand-500: #C8A24A;
  --sand-200: #EFDCA8;
  --jade-500: #1F8A70;
  --cyan-400: #2FD4C6;
  --paper-100: #F3F1EA;
  --paper-050: #FBFAF6;
  --ink-900: #14161C;
  --slate-400: #7A86A8;

  --line: rgba(11, 18, 48, .14);
  --line-strong: rgba(11, 18, 48, .28);
  --line-dark: rgba(243, 241, 234, .16);
  --on-dark: rgba(243, 241, 234, .86);
  --on-dark-muted: rgba(243, 241, 234, .70);

  --font-display: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei",
    system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-body: "Noto Serif SC", "Source Han Serif SC", "Songti SC", SimSun, Georgia, serif;
  --font-mono: ui-monospace, "JetBrains Mono", "IBM Plex Mono", "SFMono-Regular", Consolas,
    "Courier New", monospace;

  --wrap-max: 1200px;
  --gutter: clamp(1.1rem, 4vw, 3rem);
  --radius: 2px;

  --shadow-soft: 0 1px 0 rgba(11, 18, 48, .05), 0 18px 40px -30px rgba(11, 18, 48, .55);

  --dur-1: 160ms;
  --dur-2: 180ms;
  --dur-3: 220ms;
}

/* ---------- 3. 基础排版 ---------- */
body {
  background-color: var(--paper-100);
  color: var(--ink-900);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.9;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 900;
  letter-spacing: -.02em;
  line-height: 1.25;
  color: var(--indigo-950);
}

h1 { font-size: clamp(1.9rem, 4.4vw, 3.1rem); }
h2 { font-size: clamp(1.45rem, 2.9vw, 2.05rem); }
h3 { font-size: clamp(1.12rem, 2vw, 1.35rem); }

p { font-size: 1rem; }

strong { font-weight: 700; }

::selection { background: var(--sand-200); color: var(--indigo-950); }

/* ---------- 4. 布局工具 ---------- */
.wrap {
  width: 100%;
  max-width: var(--wrap-max);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section {
  position: relative;
  padding-block: clamp(3rem, 7vw, 6rem);
}

.section--tight { padding-block: clamp(1.9rem, 4vw, 3.2rem); }

.section--paper { background: var(--paper-100); color: var(--ink-900); }
.section--deep  { background: var(--indigo-950); color: var(--on-dark); }
.section--mid   { background: var(--indigo-800); color: var(--on-dark); }
.section--sand  { background: var(--sand-200); color: var(--indigo-950); }

.section--deep h1, .section--deep h2, .section--deep h3,
.section--mid  h1, .section--mid  h2, .section--mid  h3 {
  color: var(--paper-100);
}

.section--deep .eyebrow,
.section--mid  .eyebrow { color: var(--cyan-400); }

.grid {
  display: grid;
  gap: clamp(1.1rem, 3vw, 2.4rem);
}

.grid--2   { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3   { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--5-7 { grid-template-columns: 5fr 7fr; }
.grid--4-8 { grid-template-columns: 4fr 8fr; }
.grid--7-5 { grid-template-columns: 7fr 5fr; }

.divider-rule {
  height: 1px;
  border: 0;
  background: linear-gradient(90deg, transparent, var(--sand-500) 12%, var(--sand-500) 88%, transparent);
  opacity: .5;
  margin-block: clamp(1.8rem, 4vw, 3rem);
}

/* ---------- 5. 章节头 / 文本块 ---------- */
.chapter { margin-bottom: clamp(1.4rem, 3vw, 2.2rem); }

.chapter__band {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  padding-top: .85rem;
  border-top: 1px solid var(--line);
}

.section--deep .chapter__band,
.section--mid .chapter__band { border-top-color: var(--line-dark); }

.chapter__num {
  font-family: var(--font-mono);
  font-size: .8rem;
  letter-spacing: .26em;
  color: var(--sand-500);
  font-variant-numeric: tabular-nums;
}

.chapter__label {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .2em;
  color: var(--slate-400);
  text-align: right;
}

.section--deep .chapter__label,
.section--mid .chapter__label { color: var(--on-dark-muted); }

.eyebrow {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .22em;
  color: var(--slate-400);
  margin-bottom: .7rem;
}

.lede {
  font-family: var(--font-body);
  font-size: clamp(1.02rem, 1.6vw, 1.16rem);
  line-height: 1.95;
  color: var(--indigo-800);
  max-width: 62ch;
}

.section--deep .lede,
.section--mid .lede { color: var(--on-dark); }

.prose { max-width: 64ch; }

.prose p {
  font-size: 1.02rem;
  line-height: 1.95;
  color: var(--ink-900);
}

.prose p + p { margin-top: 1.05rem; }

.prose strong { color: var(--indigo-800); }

.prose ul { margin-top: 1rem; }

.prose li {
  position: relative;
  padding-left: 1.35rem;
  line-height: 1.9;
}

.prose li + li { margin-top: .4rem; }

.prose li::before {
  content: "";
  position: absolute;
  left: .15rem;
  top: .82em;
  width: 5px;
  height: 5px;
  background: var(--sand-500);
  transform: rotate(45deg);
}

.section--deep .prose p,
.section--mid .prose p { color: var(--on-dark); }

.section--deep .prose strong,
.section--mid .prose strong { color: var(--sand-200); }

.section--deep .prose li::before,
.section--mid .prose li::before { background: var(--cyan-400); }

/* ---------- 6. 刊头 ---------- */
.masthead {
  position: sticky;
  top: 0;
  z-index: 40;
  background: var(--indigo-950);
  color: var(--on-dark);
  box-shadow: 0 1px 0 rgba(200, 162, 74, .22);
}

.skip-link {
  position: absolute;
  left: 50%;
  top: 0;
  z-index: 80;
  transform: translate(-50%, -130%);
  display: inline-block;
  padding: .6rem 1.1rem;
  background: var(--sand-500);
  color: #1A1206;
  font-family: var(--font-mono);
  font-size: .8rem;
  letter-spacing: .08em;
  border-radius: 0 0 var(--radius) var(--radius);
  transition: transform var(--dur-2) ease;
}

.skip-link:focus { transform: translate(-50%, 0); }

.scroll-progress {
  position: fixed;
  inset: 0 0 auto 0;
  height: 3px;
  z-index: 60;
  pointer-events: none;
  background: rgba(243, 241, 234, .06);
}

.scroll-progress__bar {
  display: block;
  width: 100%;
  height: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--sand-500), var(--cyan-400));
  will-change: transform;
}

.masthead__inner {
  display: grid;
  grid-template-columns: 1fr auto;
  grid-template-areas:
    "brand toggle"
    "nav nav";
  align-items: center;
  gap: .55rem 1rem;
  padding-block: .8rem;
  transition: padding-block var(--dur-3) ease;
}

.masthead__meta { display: none; }

.masthead__meta-k {
  display: block;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .2em;
  color: var(--sand-200);
  font-variant-numeric: tabular-nums;
}

.masthead__meta-v {
  display: block;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .1em;
  color: var(--on-dark-muted);
  margin-top: .2rem;
}

.masthead__brand { grid-area: brand; }

.brand {
  display: inline-flex;
  align-items: center;
  gap: .8rem;
}

.brand__mark {
  flex: 0 0 auto;
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border: 1px solid rgba(200, 162, 74, .62);
  border-radius: var(--radius);
  background: linear-gradient(140deg, var(--indigo-600), var(--indigo-950));
  color: var(--sand-200);
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 1.15rem;
  line-height: 1;
  transition: width var(--dur-3) ease, height var(--dur-3) ease, font-size var(--dur-3) ease;
}

.brand__text {
  display: flex;
  flex-direction: column;
  gap: .08rem;
}

.brand__name {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 1.22rem;
  letter-spacing: -.01em;
  color: var(--paper-100);
  line-height: 1.2;
}

.brand__region {
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .18em;
  color: var(--sand-200);
}

.brand__tag {
  font-size: .875rem;
  line-height: 1.5;
  color: var(--on-dark-muted);
}

.masthead__utility { display: none; }

.masthead__utility,
.nav__foot {
  align-items: center;
  gap: .5rem;
  flex-wrap: wrap;
}

.masthead__utility { grid-area: utility; justify-content: flex-end; }

.util-btn {
  display: inline-flex;
  align-items: center;
  gap: .45rem;
  padding: .48rem .78rem;
  border: 1px solid rgba(243, 241, 234, .26);
  border-radius: var(--radius);
  background: rgba(243, 241, 234, .04);
  color: var(--on-dark);
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .1em;
  line-height: 1.4;
  transition: border-color var(--dur-1) ease, color var(--dur-1) ease, background-color var(--dur-1) ease;
}

.util-btn:hover {
  border-color: var(--cyan-400);
  color: var(--cyan-400);
  background: rgba(47, 212, 198, .08);
}

.util-btn--accent {
  border-color: rgba(200, 162, 74, .6);
  color: var(--sand-200);
  background: rgba(200, 162, 74, .1);
}

.util-btn--accent:hover {
  border-color: var(--sand-500);
  background: var(--sand-500);
  color: #1A1206;
}

.util-btn__state { color: var(--cyan-400); font-size: .72rem; }

/* ---------- 7. 导航 ---------- */
.nav {
  grid-area: nav;
  display: none;
  padding-bottom: .4rem;
}

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

.nav__list {
  display: flex;
  flex-direction: column;
  gap: .1rem;
  border-top: 1px solid var(--line-dark);
  padding-top: .6rem;
}

.nav__link {
  position: relative;
  display: block;
  padding: .6rem .2rem .7rem;
  font-family: var(--font-display);
  font-weight: 500;
  font-size: .98rem;
  letter-spacing: .01em;
  color: var(--on-dark);
  transition: color var(--dur-1) ease;
}

.nav__link::after {
  content: "";
  position: absolute;
  left: .2rem;
  right: auto;
  bottom: .35rem;
  width: calc(100% - .4rem);
  height: 1px;
  background: var(--cyan-400);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur-2) ease;
}

.nav__link:hover { color: var(--cyan-400); }
.nav__link:hover::after { transform: scaleX(1); }

.nav__link[aria-current="page"] {
  color: var(--sand-200);
  font-weight: 900;
}

.nav__link[aria-current="page"]::after {
  transform: scaleX(1);
  background: var(--sand-500);
}

.nav__foot {
  display: flex;
  margin-top: .6rem;
  padding-top: .9rem;
  border-top: 1px solid var(--line-dark);
}

.nav__toggle {
  grid-area: toggle;
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  padding: .5rem .7rem;
  border: 1px solid rgba(243, 241, 234, .28);
  border-radius: var(--radius);
  color: var(--on-dark);
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .16em;
  transition: border-color var(--dur-1) ease, color var(--dur-1) ease;
}

.nav__toggle:hover { border-color: var(--cyan-400); color: var(--cyan-400); }

.nav__bars {
  position: relative;
  width: 18px;
  height: 12px;
  display: inline-block;
  background: linear-gradient(currentColor, currentColor) 0 50% / 100% 1.5px no-repeat;
}

.nav__bars::before,
.nav__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 100%;
  height: 1.5px;
  background: currentColor;
  transition: transform var(--dur-2) ease;
}

.nav__bars::before { top: 0; }
.nav__bars::after { bottom: 0; }

.nav__toggle[aria-expanded="true"] .nav__bars { background-image: none; }
.nav__toggle[aria-expanded="true"] .nav__bars::before { transform: translateY(5px) rotate(45deg); }
.nav__toggle[aria-expanded="true"] .nav__bars::after { transform: translateY(-5px) rotate(-45deg); }

.masthead__rule {
  height: 7px;
  border-top: 1px solid rgba(200, 162, 74, .32);
  background-color: var(--indigo-800);
  background-image:
    linear-gradient(45deg, rgba(200, 162, 74, .3) 25%, transparent 25%, transparent 75%, rgba(200, 162, 74, .3) 75%),
    linear-gradient(45deg, rgba(200, 162, 74, .3) 25%, transparent 25%, transparent 75%, rgba(200, 162, 74, .3) 75%);
  background-size: 14px 14px;
  background-position: 0 0, 7px 7px;
}

/* ---------- 8. 页脚 ---------- */
.site-foot {
  position: relative;
  margin-top: clamp(3rem, 7vw, 6rem);
  background: var(--indigo-950);
  color: var(--on-dark);
}

.foot__rule {
  height: 7px;
  border-top: 1px solid rgba(200, 162, 74, .4);
  background-color: rgba(200, 162, 74, .08);
  background-image:
    linear-gradient(45deg, rgba(200, 162, 74, .38) 25%, transparent 25%, transparent 75%, rgba(200, 162, 74, .38) 75%),
    linear-gradient(45deg, rgba(200, 162, 74, .38) 25%, transparent 25%, transparent 75%, rgba(200, 162, 74, .38) 75%);
  background-size: 14px 14px;
  background-position: 0 0, 7px 7px;
}

.foot__top {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.4rem;
  padding-block: clamp(1.8rem, 4vw, 2.8rem);
  border-bottom: 1px solid var(--line-dark);
}

.foot__logo {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(1.35rem, 3vw, 1.75rem);
  letter-spacing: -.02em;
  color: var(--paper-100);
}

.foot__sign {
  margin-top: .4rem;
  font-size: .9rem;
  color: var(--on-dark-muted);
}

.foot__cta-text {
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .16em;
  color: var(--sand-200);
  margin-bottom: .7rem;
}

.foot__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(1.6rem, 4vw, 2.4rem);
  padding-block: clamp(2rem, 5vw, 3.2rem);
}

.foot__title {
  font-family: var(--font-mono);
  font-weight: 400;
  font-size: .76rem;
  letter-spacing: .2em;
  color: var(--sand-200);
  margin-bottom: .85rem;
}

.foot__list li + li { margin-top: .35rem; }

.foot__link {
  position: relative;
  display: inline-block;
  padding-block: .12rem;
  font-size: .92rem;
  line-height: 1.7;
  color: rgba(243, 241, 234, .8);
  transition: color var(--dur-1) ease;
}

.foot__link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 1px;
  background: var(--cyan-400);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur-2) ease;
}

.foot__link:hover { color: var(--cyan-400); }
.foot__link:hover::after { transform: scaleX(1); }

.foot__link--mono {
  font-family: var(--font-mono);
  font-size: .84rem;
  letter-spacing: .02em;
  color: var(--cyan-400);
  word-break: break-all;
}

.foot__list--contact { display: grid; gap: .85rem; }

.foot__contact-item { display: block; }

.foot__contact-label {
  display: block;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .2em;
  color: var(--sand-200);
  margin-bottom: .2rem;
}

.foot__contact-value {
  display: block;
  font-size: .9rem;
  line-height: 1.75;
  color: rgba(243, 241, 234, .84);
}

.foot__note {
  margin-top: .9rem;
  font-size: .88rem;
  line-height: 1.7;
  color: var(--on-dark-muted);
}

.foot__legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .8rem 1.4rem;
  padding-block: 1.2rem 1.6rem;
  border-top: 1px solid var(--line-dark);
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .06em;
  color: var(--on-dark-muted);
}

.foot__copy { font-size: .78rem; }

.foot__legal-links {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem 1.2rem;
}

.foot__legal-links .foot__link { font-size: .78rem; }

.foot__icp { font-size: .78rem; }

.to-top {
  margin-left: auto;
  display: inline-flex;
  align-items: center;
  padding: .45rem .75rem;
  border: 1px solid rgba(200, 162, 74, .5);
  border-radius: var(--radius);
  color: var(--sand-200);
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .12em;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity var(--dur-3) ease, transform var(--dur-3) ease, visibility var(--dur-3) ease,
    background-color var(--dur-1) ease, color var(--dur-1) ease;
}

.to-top[data-visible] {
  opacity: 1;
  visibility: visible;
  transform: none;
}

.to-top:hover { background: var(--sand-500); color: #1A1206; }

/* ---------- 9. 按钮与链接 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  padding: .82rem 1.35rem;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: .95rem;
  letter-spacing: .02em;
  line-height: 1.2;
  transition: background-color var(--dur-1) ease, color var(--dur-1) ease, border-color var(--dur-1) ease;
}

.btn--primary {
  background: var(--sand-500);
  color: #1A1206;
}

.btn--primary:hover { background: var(--sand-200); }

.btn--ghost {
  border-color: rgba(200, 162, 74, .55);
  color: var(--sand-200);
}

.btn--ghost:hover {
  background: var(--sand-500);
  border-color: var(--sand-500);
  color: #1A1206;
}

.btn--quiet {
  border-color: var(--line-strong);
  color: var(--indigo-950);
}

.btn--quiet:hover {
  border-color: var(--indigo-950);
  background: var(--indigo-950);
  color: var(--paper-100);
}

.link-underline {
  position: relative;
  color: var(--indigo-800);
  font-weight: 700;
}

.link-underline::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -.14em;
  width: 100%;
  height: 1px;
  background: var(--sand-500);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur-2) ease;
}

.link-underline:hover::after { transform: scaleX(1); }

/* ---------- 10. 卡片 / 标签 / 统计 ---------- */
.card {
  position: relative;
  display: block;
  padding: 1.35rem 1.5rem 1.5rem;
  background: var(--paper-050);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color var(--dur-1) ease, background-color var(--dur-1) ease,
    box-shadow var(--dur-1) ease;
}

.card::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  width: 4px;
  background: var(--cyan-400);
  transform: translateX(100%);
  transition: transform var(--dur-1) ease;
}

.card:hover,
.card:focus-within {
  border-color: rgba(31, 138, 112, .55);
  background: #fff;
  box-shadow: var(--shadow-soft);
}

.card:hover::before,
.card:focus-within::before { transform: translateX(0); }

.card__meta {
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .16em;
  color: var(--slate-400);
  font-variant-numeric: tabular-nums;
}

.card__title {
  margin-top: .5rem;
  font-size: 1.08rem;
  color: var(--indigo-950);
}

.card__body {
  margin-top: .55rem;
  font-size: .95rem;
  line-height: 1.85;
  color: var(--indigo-800);
}

.card__foot {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .55rem;
  margin-top: 1rem;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: .35rem;
  padding: .22rem .55rem;
  border: 1px solid transparent;
  border-radius: 1px;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .12em;
  line-height: 1.5;
}

.tag--updated {
  color: #0E5A48;
  background: rgba(31, 138, 112, .12);
  border-color: rgba(31, 138, 112, .35);
}

.tag--download {
  color: #6B5316;
  background: rgba(200, 162, 74, .16);
  border-color: rgba(200, 162, 74, .42);
}

.tag--archived {
  color: #3B4460;
  background: rgba(122, 134, 168, .16);
  border-color: rgba(122, 134, 168, .38);
}

.stat-strip {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.stat {
  padding: 1.3rem 1.2rem 1.4rem;
  background: var(--paper-050);
}

.stat__num {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(1.55rem, 3vw, 2.15rem);
  letter-spacing: -.02em;
  color: var(--indigo-950);
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
}

.stat__num em {
  font-style: normal;
  font-size: .5em;
  color: var(--sand-500);
  margin-left: .18em;
}

.stat__label {
  margin-top: .45rem;
  font-family: var(--font-mono);
  font-size: .74rem;
  letter-spacing: .14em;
  color: var(--slate-400);
}

/* ---------- 11. 折叠面板 ---------- */
.acc { border-top: 1px solid var(--line); }

.acc__item { border-bottom: 1px solid var(--line); }

.acc__btn {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  width: 100%;
  padding: 1.1rem .2rem;
  text-align: left;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.02rem;
  letter-spacing: -.01em;
  color: var(--indigo-950);
  transition: color var(--dur-1) ease;
}

.acc__btn:hover { color: var(--jade-500); }

.acc__btn::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-weight: 400;
  font-size: 1.15rem;
  line-height: 1.1;
  color: var(--sand-500);
  transition: transform var(--dur-3) ease;
}

.acc__btn[aria-expanded="true"]::after {
  content: "–";
  transform: rotate(180deg);
}

.acc__panel {
  height: 0;
  overflow: hidden;
  transition: height var(--dur-3) ease;
}

.acc__panel-inner {
  max-width: 72ch;
  padding: .2rem 0 1.4rem;
  font-size: .98rem;
  line-height: 1.9;
  color: var(--indigo-800);
}

/* ---------- 12. 标签筛选 ---------- */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .5rem;
}

.filter-chip {
  padding: .42rem .8rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .1em;
  color: var(--indigo-800);
  transition: border-color var(--dur-1) ease, background-color var(--dur-1) ease,
    color var(--dur-1) ease;
}

.filter-chip:hover { border-color: var(--sand-500); }

.filter-chip[aria-pressed="true"] {
  background: var(--indigo-950);
  border-color: var(--indigo-950);
  color: var(--sand-200);
}

/* ---------- 13. 侧边章节索引 ---------- */
.index-rail {
  position: sticky;
  top: 150px;
  font-family: var(--font-mono);
  font-size: .78rem;
}

.index-rail__item + .index-rail__item { margin-top: .15rem; }

.index-rail__link {
  display: block;
  padding: .42rem .2rem .42rem .8rem;
  border-left: 1px solid var(--line);
  letter-spacing: .08em;
  color: var(--slate-400);
  transition: color var(--dur-1) ease, border-color var(--dur-1) ease;
}

.index-rail__link:hover {
  color: var(--indigo-950);
  border-left-color: var(--sand-500);
}

.index-rail__link.is-active,
.index-rail__link[aria-current] {
  color: var(--indigo-950);
  font-weight: 700;
  border-left-color: var(--sand-500);
}

.section--deep .index-rail__link { color: var(--on-dark-muted); }
.section--deep .index-rail__link:hover,
.section--deep .index-rail__link.is-active { color: var(--sand-200); }

/* ---------- 14. 面包屑 ---------- */
.crumbs {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .06em;
  color: var(--slate-400);
}

.crumbs__item { display: inline-flex; align-items: center; gap: .5rem; }

.crumbs__item::after {
  content: "/";
  color: rgba(122, 134, 168, .65);
}

.crumbs__item:last-child::after { content: ""; }

.crumbs a { color: var(--indigo-800); transition: color var(--dur-1) ease; }
.crumbs a:hover { color: var(--jade-500); }

/* ---------- 15. 图片容器 ---------- */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(145deg, var(--indigo-800), var(--indigo-950));
  isolation: isolate;
}

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

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

.media-frame__label {
  position: absolute;
  left: .8rem;
  bottom: .8rem;
  z-index: 2;
  padding: .2rem .5rem;
  background: rgba(11, 18, 48, .72);
  border: 1px solid rgba(200, 162, 74, .45);
  border-radius: 1px;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .14em;
  color: var(--sand-200);
}

/* ---------- 16. 主内容与入场 ---------- */
#main-content { display: block; scroll-margin-top: 140px; }

.main { display: block; }

.js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 420ms ease, transform 420ms ease;
}

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

/* ---------- 17. 响应式：平板与桌面 ---------- */
@media (min-width: 640px) {
  .foot__top { grid-template-columns: 1fr auto; align-items: end; }
  .foot__cta { text-align: right; }
  .foot__grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 900px) {
  .masthead__inner {
    grid-template-columns: 1fr auto 1fr;
    grid-template-areas:
      "meta brand utility"
      "nav nav nav";
    gap: .2rem 1.5rem;
    padding-block: 1.15rem .95rem;
  }

  .masthead__meta { display: block; grid-area: meta; }

  .masthead__brand { justify-self: center; text-align: center; }

  .brand { flex-direction: row; align-items: center; }

  .masthead__utility { display: flex; }

  .nav { display: block; padding-bottom: 0; }

  .nav__list {
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
    gap: .15rem .35rem;
    border-top: 0;
    padding-top: 0;
  }

  .nav__link {
    padding: .5rem .85rem .8rem;
    font-size: .95rem;
  }

  .nav__link::after { left: .85rem; width: calc(100% - 1.7rem); }

  .nav__toggle { display: none; }

  .nav__foot { display: none; }

  .foot__grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }

  .grid--4-8, .grid--5-7, .grid--7-5 { grid-template-columns: revert; }

  .grid--4-8 { grid-template-columns: 4fr 8fr; }
  .grid--5-7 { grid-template-columns: 5fr 7fr; }
  .grid--7-5 { grid-template-columns: 7fr 5fr; }
}

/* 刊头压缩态（仅桌面） */
@media (min-width: 900px) {
  .masthead[data-condensed] .masthead__inner {
    grid-template-columns: auto 1fr auto;
    grid-template-areas: "brand nav utility";
    align-items: center;
    padding-block: .5rem;
  }

  .masthead[data-condensed] .masthead__meta { display: none; }
  .masthead[data-condensed] .brand__tag { display: none; }
  .masthead[data-condensed] .brand { justify-self: start; text-align: left; }
  .masthead[data-condensed] .brand__mark { width: 32px; height: 32px; font-size: .92rem; }
  .masthead[data-condensed] .brand__name { font-size: 1.02rem; }
  .masthead[data-condensed] .brand__region { font-size: .64rem; letter-spacing: .14em; }
  .masthead[data-condensed] .nav__link { padding-bottom: .5rem; }
}

@media (max-width: 899px) {
  .grid--2, .grid--3, .grid--4-8, .grid--5-7, .grid--7-5 { grid-template-columns: minmax(0, 1fr); }
  .index-rail { position: static; top: auto; }
  .to-top { margin-left: 0; }
}

@media (max-width: 480px) {
  body { font-size: 16px; }
  .brand__tag { display: none; }
  .foot__legal { gap: .6rem .9rem; }
}

/* ---------- 18. 无障碍与降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

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

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

@media print {
  .masthead, .site-foot, .scroll-progress, .to-top { display: none !important; }
  body { background: #fff; color: #000; }
}