/* =========================================================
   开全中心 · /assets/site.css
   共享外壳：reset / 令牌 / 中文排版 / 头部 / 页脚 / 基础组件
   ========================================================= */

/* ---------- 1. RESET ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body, h1, h2, h3, h4, p, ul, ol, figure, blockquote { margin: 0; }
ul, ol { padding: 0; list-style: none; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }
img, svg { max-width: 100%; display: block; }
img { height: auto; }

/* ---------- 2. 设计令牌 ---------- */
:root {
  --void: #061426;
  --hull: #0B2138;
  --accent: #21E6C1;
  --accent-soft: #7FF7E4;
  --amber: #FFB547;
  --amber-deep: #8A5A12;
  --glass: rgba(233, 244, 255, 0.08);
  --glass-strong: rgba(233, 244, 255, 0.14);
  --text-body: #C6D6E4;
  --text-mute: #8DA3B8;
  --text-title: #F4FAFF;
  --ok: #3DDC97;

  --line: rgba(127, 247, 228, 0.16);
  --line-soft: rgba(141, 163, 184, 0.22);

  --font-display: "Barlow Condensed", "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "Roboto Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --shell-w: 1240px;
  --header-h: 78px;
  --radius-s: 10px;
  --radius-m: 16px;
  --radius-l: 22px;
  --gap: clamp(20px, 3.4vw, 40px);
  --section-y: clamp(72px, 9vw, 150px);
}

/* ---------- 3. 基底与氛围 ---------- */
body {
  min-height: 100%;
  background-color: var(--void);
  color: var(--text-body);
  font-family: var(--font-body);
  font-size: clamp(15px, 1.1vw, 17px);
  line-height: 1.85;
  font-weight: 400;
  letter-spacing: 0.01em;
  overflow-x: hidden;
}
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(920px 620px at 76% -12%, rgba(33, 230, 193, 0.12), transparent 70%),
    radial-gradient(700px 520px at 6% 4%, rgba(33, 230, 193, 0.06), transparent 74%),
    radial-gradient(800px 700px at 50% 108%, rgba(255, 181, 71, 0.05), transparent 72%),
    linear-gradient(180deg, #061426 0%, #08192e 46%, #061426 100%);
}
body > * { position: relative; z-index: 1; }

::selection { background: rgba(33, 230, 193, 0.32); color: var(--text-title); }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ---------- 4. 排版 ---------- */
h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--text-title);
  font-weight: 800;
  line-height: 1.06;
  letter-spacing: -0.02em;
}
h1 { font-size: clamp(44px, 8vw, 96px); }
h2 { font-size: clamp(30px, 4.4vw, 56px); }
h3 { font-size: clamp(22px, 2.4vw, 28px); }
h4 { font-size: clamp(18px, 1.6vw, 22px); font-weight: 700; }

p { max-width: 34em; }
strong { color: var(--text-title); font-weight: 700; }

code, .mono { font-family: var(--font-mono); letter-spacing: 0.08em; }

/* ---------- 5. 布局外壳 ---------- */
.shell {
  width: 100%;
  max-width: var(--shell-w);
  margin-inline: auto;
  padding-inline: clamp(20px, 4.6vw, 56px);
}
.section { padding-block: var(--section-y); }
.section-head { max-width: 46em; margin-bottom: clamp(28px, 4vw, 56px); }
.lede {
  font-size: clamp(17px, 1.5vw, 21px);
  line-height: 1.75;
  color: var(--text-body);
  max-width: 34em;
}
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.22em;
  color: var(--accent);
  text-transform: uppercase;
  margin-bottom: 16px;
}
.eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  background: var(--accent);
  opacity: 0.7;
}
.divider {
  height: 1px;
  border: 0;
  background: linear-gradient(90deg, var(--accent) 0%, rgba(127, 247, 228, 0.12) 42%, transparent 100%);
  opacity: 0.6;
  margin-block: clamp(40px, 6vw, 84px);
}
.rule-band {
  height: 2px;
  background: linear-gradient(90deg, transparent, rgba(33, 230, 193, 0.5), rgba(255, 181, 71, 0.35), transparent);
  opacity: 0.7;
}
.stack > * + * { margin-top: clamp(16px, 2vw, 28px); }

.grid { display: grid; gap: var(--gap); }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--split { grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); align-items: start; }

/* ---------- 6. 章节长卷 ---------- */
.chapter { padding-block: clamp(64px, 9vw, 148px); }
.chapter-head {
  display: flex;
  gap: clamp(18px, 3.4vw, 54px);
  align-items: flex-start;
  margin-bottom: clamp(28px, 4vw, 60px);
}
.chapter-num {
  flex: 0 0 auto;
  font-family: var(--font-display);
  font-size: clamp(58px, 10vw, 118px);
  font-weight: 800;
  line-height: 0.8;
  letter-spacing: -0.03em;
  color: transparent;
  -webkit-text-stroke: 1.5px rgba(33, 230, 193, 0.48);
}
.chapter-title { max-width: 18em; }
.chapter-sub {
  margin-top: 14px;
  font-size: clamp(15px, 1.2vw, 18px);
  color: var(--text-mute);
  max-width: 32em;
  line-height: 1.8;
}
.side-note {
  writing-mode: vertical-rl;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.34em;
  color: var(--text-mute);
  align-self: stretch;
}

/* ---------- 7. 按钮与链接 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 0.78em 1.5em;
  border-radius: 999px;
  border: 1px solid transparent;
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.02em;
  line-height: 1.3;
  white-space: nowrap;
  transition: transform 0.22s ease, background-color 0.22s ease, color 0.22s ease,
              border-color 0.22s ease, box-shadow 0.22s ease, opacity 0.22s ease;
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }
.btn--solid {
  background: var(--accent);
  color: #04141f;
  border-color: var(--accent);
  box-shadow: 0 10px 30px -14px rgba(33, 230, 193, 0.75);
}
.btn--solid:hover { background: var(--accent-soft); border-color: var(--accent-soft); }
.btn--ghost {
  background: rgba(233, 244, 255, 0.04);
  color: var(--text-title);
  border-color: var(--line);
}
.btn--ghost:hover { border-color: var(--accent); color: var(--accent-soft); background: rgba(33, 230, 193, 0.08); }
.btn--amber {
  background: var(--amber);
  color: #2b1a00;
  border-color: var(--amber);
}
.btn--amber:hover { background: #ffc76a; border-color: #ffc76a; }
.btn--sm { padding: 0.6em 1.15em; font-size: 14px; }
.btn-row { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }

.text-link {
  color: var(--accent-soft);
  border-bottom: 1px dashed rgba(127, 247, 228, 0.5);
  padding-bottom: 1px;
  transition: color 0.2s ease, border-color 0.2s ease;
}
.text-link:hover { color: var(--accent); border-bottom-color: var(--accent); }

/* ---------- 8. 头部 ---------- */
.skip-link {
  position: absolute;
  left: 16px;
  top: -80px;
  z-index: 300;
  padding: 10px 20px;
  border-radius: 0 0 12px 12px;
  background: var(--accent);
  color: #04141f;
  font-weight: 700;
  font-size: 14px;
  transition: top 0.22s ease;
}
.skip-link:focus { top: 0; }

.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background-color 0.35s ease, border-color 0.35s ease,
              backdrop-filter 0.35s ease, box-shadow 0.35s ease;
}
.site-header.is-condensed {
  background: rgba(6, 20, 38, 0.88);
  backdrop-filter: blur(16px) saturate(140%);
  -webkit-backdrop-filter: blur(16px) saturate(140%);
  border-bottom-color: var(--line);
  box-shadow: 0 18px 40px -30px rgba(0, 0, 0, 0.9);
}
.header-inner {
  position: relative;
  z-index: 2;
  display: flex;
  align-items: center;
  gap: clamp(16px, 3vw, 44px);
  min-height: var(--header-h);
  padding-block: 12px;
}
.site-header.is-condensed .header-inner { min-height: 66px; padding-block: 8px; }

.brand { display: inline-flex; align-items: center; gap: 12px; flex: 0 0 auto; }
.brand-mark {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: linear-gradient(150deg, rgba(33, 230, 193, 0.22), rgba(33, 230, 193, 0.04));
  color: var(--accent);
  font-family: var(--font-display);
  font-size: 21px;
  font-weight: 800;
  line-height: 1;
}
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-name {
  font-family: var(--font-display);
  font-size: 21px;
  font-weight: 800;
  letter-spacing: 0.04em;
  color: var(--text-title);
}
.brand-tag {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--text-mute);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: clamp(16px, 2.4vw, 36px);
  margin-left: auto;
}
.nav-list { display: flex; align-items: center; gap: clamp(6px, 1.4vw, 22px); }
.nav-list { order: 1; }
.nav-actions { order: 2; display: flex; align-items: center; gap: 10px; }
.nav-link {
  position: relative;
  display: inline-block;
  padding: 8px 4px;
  font-size: 15px;
  font-weight: 500;
  color: var(--text-body);
  transition: color 0.2s ease;
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 4px;
  right: 4px;
  bottom: 2px;
  height: 1px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.26s ease;
}
.nav-link:hover { color: var(--text-title); }
.nav-link:hover::after { transform: scaleX(1); }
.nav-link[aria-current="page"] { color: var(--accent); font-weight: 700; }
.nav-link[aria-current="page"]::after { transform: scaleX(1); }
.nav-link[aria-current="page"]::before {
  content: "";
  position: absolute;
  left: -10px;
  top: 50%;
  width: 5px;
  height: 5px;
  margin-top: -2.5px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px rgba(33, 230, 193, 0.16);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  margin-left: auto;
  padding: 9px 14px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--glass);
  color: var(--text-title);
  font-size: 14px;
  font-weight: 600;
}
.nav-toggle-bars {
  position: relative;
  display: block;
  width: 18px;
  height: 12px;
}
.nav-toggle-bars::before,
.nav-toggle-bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 18px;
  height: 1.5px;
  background: var(--accent);
  transition: transform 0.28s ease, top 0.28s ease, opacity 0.2s ease;
}
.nav-toggle-bars::before { top: 2px; }
.nav-toggle-bars::after { top: 9px; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::before { top: 5.5px; transform: rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::after { top: 5.5px; transform: rotate(-45deg); }
.nav-toggle-label { letter-spacing: 0.06em; }

html.nav-open { overflow: hidden; }

/* ---------- 9. 页脚 ---------- */
.site-footer {
  margin-top: clamp(60px, 8vw, 130px);
  border-top: 1px solid var(--line);
  background:
    radial-gradient(700px 340px at 84% 0%, rgba(33, 230, 193, 0.08), transparent 72%),
    linear-gradient(180deg, rgba(11, 33, 56, 0.92), rgba(6, 20, 38, 0.98));
}
.footer-top {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 1.5fr);
  gap: clamp(32px, 5vw, 76px);
  padding-block: clamp(44px, 6vw, 78px);
}
.footer-brand { display: flex; flex-direction: column; gap: 14px; }
.footer-brand-name {
  font-family: var(--font-display);
  font-size: clamp(26px, 2.6vw, 34px);
  font-weight: 800;
  letter-spacing: 0.03em;
  color: var(--text-title);
}
.footer-brand-tag {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.26em;
  color: var(--accent);
}
.footer-contact,
.footer-service {
  font-size: 14px;
  line-height: 1.9;
  color: var(--text-body);
  max-width: 34em;
}
.footer-service { color: var(--text-mute); font-size: 13px; }

.footer-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 40px);
}
.footer-col-title {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.24em;
  color: var(--text-mute);
  margin-bottom: 16px;
}
.footer-links { display: flex; flex-direction: column; gap: 10px; }
.footer-link {
  font-size: 15px;
  color: var(--text-body);
  transition: color 0.2s ease, transform 0.2s ease;
}
.footer-link:hover { color: var(--accent); transform: translateX(3px); }

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding-block: 22px 30px;
  border-top: 1px solid var(--line-soft);
}
.footer-legal,
.footer-meta {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--text-mute);
  max-width: none;
}

/* ---------- 10. 面包屑 ---------- */
.breadcrumb { padding-top: calc(var(--header-h) + 26px); }
.breadcrumb-list { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.breadcrumb-item { display: inline-flex; align-items: center; gap: 8px; }
.breadcrumb-link,
.breadcrumb-item[aria-current="page"] {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--text-mute);
}
.breadcrumb-link:hover { color: var(--accent); }
.breadcrumb-item[aria-current="page"] { color: var(--accent); }
.breadcrumb-sep { color: rgba(141, 163, 184, 0.5); font-size: 12px; }

/* ---------- 11. 卡片与数据 ---------- */
.glass-card {
  position: relative;
  padding: clamp(22px, 2.6vw, 34px);
  border-radius: var(--radius-l);
  border: 1px solid var(--line);
  background: var(--glass);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  transition: transform 0.3s ease, background-color 0.3s ease, border-color 0.3s ease;
}
.glass-card:hover {
  transform: translateY(-4px);
  background: var(--glass-strong);
  border-color: rgba(127, 247, 228, 0.34);
}
.solid-card {
  padding: clamp(22px, 2.6vw, 34px);
  border-radius: var(--radius-m);
  border: 1px solid var(--line-soft);
  background: var(--hull);
}
.metric-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: clamp(16px, 2vw, 28px);
}
.metric { display: flex; flex-direction: column; gap: 6px; }
.metric-value {
  font-family: var(--font-mono);
  font-size: clamp(26px, 3vw, 40px);
  font-weight: 700;
  letter-spacing: 0.06em;
  line-height: 1.1;
  color: var(--amber);
}
.metric--accent .metric-value { color: var(--accent); }
.metric--plain .metric-value { color: var(--text-title); }
.metric-label {
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--text-mute);
  max-width: none;
}
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border-radius: 999px;
  border: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--text-mute);
}
.badge--accent { color: var(--accent); border-color: rgba(33, 230, 193, 0.42); background: rgba(33, 230, 193, 0.08); }
.badge--amber { color: var(--amber); border-color: rgba(255, 181, 71, 0.45); background: rgba(138, 90, 18, 0.28); }
.status-dot {
  display: inline-block;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--ok);
  box-shadow: 0 0 0 4px rgba(61, 220, 151, 0.16);
}

/* ---------- 12. 版本对照色带 ---------- */
.compare-band {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  border-radius: var(--radius-m);
  overflow: hidden;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}
.compare-col {
  padding: clamp(22px, 2.6vw, 34px);
  background: var(--hull);
  display: flex;
  flex-direction: column;
  gap: 18px;
}
.compare-col--alt {
  background:
    linear-gradient(180deg, rgba(33, 230, 193, 0.09), rgba(11, 33, 56, 0.96) 55%),
    var(--hull);
}
.compare-list { display: flex; flex-direction: column; gap: 12px; }
.compare-item {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  padding-bottom: 10px;
  border-bottom: 1px dashed rgba(141, 163, 184, 0.18);
  font-size: 15px;
}
.compare-item:last-child { border-bottom: 0; padding-bottom: 0; }
.compare-item .mono { font-family: var(--font-mono); font-size: 15px; color: var(--text-title); }
.compare-item.is-diff .mono { color: var(--amber); }

/* ---------- 13. 流程与时间轴 ---------- */
.step-bar {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: clamp(14px, 2vw, 26px);
}
.step-item {
  padding-top: 18px;
  border-top: 1px solid var(--line);
}
.step-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.2em;
  color: var(--accent);
  margin-bottom: 10px;
}
.step-title { font-size: 16px; font-weight: 600; color: var(--text-title); line-height: 1.6; }

.timeline { display: flex; flex-direction: column; gap: 0; }
.timeline-item {
  display: grid;
  grid-template-columns: 130px minmax(0, 1fr);
  gap: clamp(16px, 3vw, 40px);
  padding-block: clamp(20px, 2.4vw, 30px);
  border-bottom: 1px solid var(--line-soft);
}
.timeline-mark {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.14em;
  color: var(--amber);
}
.timeline-body { font-size: 15px; color: var(--text-body); }
.timeline-meta {
  margin-top: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--text-mute);
}

/* ---------- 14. 折叠面板 ---------- */
.disclosure {
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-m);
  background: rgba(11, 33, 56, 0.6);
  overflow: hidden;
  transition: border-color 0.25s ease, background-color 0.25s ease;
}
.disclosure + .disclosure { margin-top: 12px; }
.disclosure.is-open { border-color: rgba(33, 230, 193, 0.34); background: rgba(11, 33, 56, 0.86); }
.disclosure-toggle {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  width: 100%;
  padding: clamp(16px, 1.8vw, 22px) clamp(18px, 2.2vw, 28px);
  text-align: left;
  color: var(--text-title);
}
.disclosure-title { font-size: 16px; font-weight: 600; line-height: 1.6; }
.disclosure-icon {
  position: relative;
  flex: 0 0 auto;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  border: 1px solid var(--line);
}
.disclosure-icon::before,
.disclosure-icon::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  background: var(--accent);
  transform: translate(-50%, -50%);
}
.disclosure-icon::before { width: 8px; height: 1.5px; }
.disclosure-icon::after { width: 1.5px; height: 8px; transition: transform 0.25s ease, opacity 0.25s ease; }
.disclosure.is-open .disclosure-icon::after { transform: translate(-50%, -50%) scaleY(0); opacity: 0; }
.disclosure-panel {
  padding: 0 clamp(18px, 2.2vw, 28px) clamp(18px, 2.2vw, 26px);
  font-size: 15px;
  color: var(--text-body);
  animation: panelIn 0.32s ease both;
}
@keyframes panelIn { from { opacity: 0; transform: translateY(-6px); } to { opacity: 1; transform: none; } }

/* ---------- 15. 图片容器 ---------- */
.media-frame {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-m);
  border: 1px solid var(--line);
  aspect-ratio: 16 / 9;
  background:
    linear-gradient(140deg, rgba(33, 230, 193, 0.12), rgba(6, 20, 38, 0) 58%),
    repeating-linear-gradient(90deg, rgba(127, 247, 228, 0.07) 0 1px, transparent 1px 46px),
    repeating-linear-gradient(0deg, rgba(127, 247, 228, 0.07) 0 1px, transparent 1px 46px),
    var(--hull);
}
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  position: relative;
  z-index: 1;
}
.media-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--gap);
}
.media-figure { display: flex; flex-direction: column; gap: 12px; }
.media-caption {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--text-mute);
  max-width: 40em;
}

/* ---------- 16. 正文容器 ---------- */
.prose { max-width: 40em; }
.prose > * + * { margin-top: 1.15em; }
.prose h2 { margin-top: 1.8em; }
.prose h3 { margin-top: 1.6em; }
.prose ul, .prose ol { padding-left: 1.3em; max-width: 34em; }
.prose ul li { list-style: none; position: relative; padding-left: 16px; }
.prose ul li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.85em;
  width: 6px;
  height: 1.5px;
  background: var(--accent);
}
.prose ol { list-style: decimal; }
.prose li + li { margin-top: 0.5em; }
.prose blockquote {
  padding-left: 20px;
  border-left: 2px solid var(--accent);
  color: var(--text-mute);
}

/* ---------- 17. 滚动与章节指示 ---------- */
.scroll-progress {
  position: fixed;
  left: 0;
  top: 0;
  z-index: 140;
  width: 100%;
  height: 2px;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--accent), var(--accent-soft) 60%, var(--amber));
}
.chapter-rail {
  position: fixed;
  right: clamp(10px, 1.8vw, 26px);
  top: 50%;
  transform: translateY(-50%);
  z-index: 80;
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding: 14px 8px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: rgba(6, 20, 38, 0.6);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}
.rail-node {
  display: block;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  border: 1px solid rgba(127, 247, 228, 0.5);
  background: transparent;
  transition: background-color 0.25s ease, box-shadow 0.25s ease, transform 0.25s ease;
}
.rail-node:hover { background: var(--accent-soft); transform: scale(1.15); }
.rail-node[aria-current="true"] {
  background: var(--accent);
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(33, 230, 193, 0.18);
}

.to-top {
  position: fixed;
  right: clamp(14px, 2.4vw, 34px);
  bottom: clamp(18px, 3vw, 36px);
  z-index: 90;
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  border: 1px solid var(--line);
  background: rgba(6, 20, 38, 0.82);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 15px;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 0.28s ease, transform 0.28s ease, visibility 0.28s ease, border-color 0.2s ease;
}
.to-top.is-visible { opacity: 1; visibility: visible; transform: none; }
.to-top:hover { border-color: var(--accent); }

/* ---------- 18. 显现动效 ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.62s ease, transform 0.62s cubic-bezier(0.22, 0.61, 0.36, 1);
  will-change: opacity, transform;
}
[data-reveal].is-revealed { opacity: 1; transform: none; }

/* ---------- 19. 工具类 ---------- */
.visually-hidden {
  position: absolute !important;
  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;
}

/* ---------- 20. 响应式 ---------- */
@media (max-width: 1080px) {
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--split { grid-template-columns: minmax(0, 1fr); }
  .footer-top { grid-template-columns: minmax(0, 1fr); }
  .chapter-rail { display: none; }
}

@media (max-width: 900px) {
  :root { --header-h: 68px; }

  .brand-tag { display: none; }
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: fixed;
    inset: 0;
    z-index: 95;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 26px;
    margin-left: 0;
    padding: calc(var(--header-h) + 26px) clamp(20px, 6vw, 42px) 44px;
    overflow-y: auto;
    background: rgba(6, 20, 38, 0.94);
    backdrop-filter: blur(20px) saturate(130%);
    -webkit-backdrop-filter: blur(20px) saturate(130%);
    border-bottom: 1px solid var(--line);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: opacity 0.3s ease, transform 0.3s ease, visibility 0.3s ease;
  }
  .site-nav[data-open="true"] { opacity: 1; visibility: visible; transform: none; }

  .nav-actions {
    order: 1;
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
  }
  .nav-actions .btn { width: 100%; padding: 0.95em 0.8em; }

  .nav-list {
    order: 2;
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
  }
  .nav-link {
    display: block;
    padding: 16px 4px;
    font-family: var(--font-display);
    font-size: 26px;
    font-weight: 700;
    letter-spacing: 0.02em;
    border-bottom: 1px solid var(--line-soft);
  }
  .nav-link::after { display: none; }
  .nav-link[aria-current="page"]::before { left: -2px; }

  .grid--2, .grid--3 { grid-template-columns: minmax(0, 1fr); }
  .compare-band { grid-template-columns: minmax(0, 1fr); }
  .step-bar { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .timeline-item { grid-template-columns: minmax(0, 1fr); gap: 8px; }
  .chapter-head { flex-direction: column; gap: 12px; }
  .side-note { writing-mode: horizontal-tb; letter-spacing: 0.22em; }
}

@media (max-width: 640px) {
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .step-bar { grid-template-columns: minmax(0, 1fr); }
  h1 { font-size: clamp(36px, 12vw, 56px); }
  .chapter-num { font-size: clamp(48px, 16vw, 78px); -webkit-text-stroke-width: 1px; }
  .btn { width: 100%; }
  .btn-row { flex-direction: column; align-items: stretch; }
}

/* ---------- 21. 无障碍与降级 ---------- */
@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;
    scroll-behavior: auto !important;
  }
  [data-reveal] { opacity: 1 !important; transform: none !important; }
  .glass-card:hover, .btn:hover, .footer-link:hover { transform: none; }
}