/* ==========================================================================
   新银河 · 共享样式表 /assets/site.css
   框架式导航：顶栏 + 左右固定导轨；内容主区居中
   ========================================================================== */

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

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

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

ul, ol { list-style: none; }

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

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

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

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

/* ---------- tokens ---------- */
:root {
  --c-void: #060A1A;
  --c-indigo: #0E1533;
  --c-panel: #172049;
  --c-silver: #E9EEFA;
  --c-dust: #9BA6C6;
  --c-cyan: #38E1D2;
  --c-blue: #4C8DFF;
  --c-gold: #F3C46A;
  --c-gold-deep: #B8892F;
  --c-glass: rgba(233, 238, 250, 0.06);
  --c-line: rgba(233, 238, 250, 0.12);
  --c-line-soft: rgba(233, 238, 250, 0.08);
  --c-body: #D7DEEE;

  --font-display: "HarmonyOS Sans SC", "Source Han Sans SC", "PingFang SC", sans-serif;
  --font-body: "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, "Noto Sans Mono CJK SC", monospace;

  --bar-h: 64px;
  --rail-l: 232px;
  --rail-r: 284px;

  --ease: cubic-bezier(0.2, 0.7, 0.3, 1);
  --radius: 14px;
}

/* ---------- base ---------- */
body {
  min-height: 100vh;
  padding-top: var(--bar-h);
  color: var(--c-silver);
  font-family: var(--font-body);
  font-size: 16px;
  font-weight: 400;
  line-height: 1.9;
  background-color: var(--c-void);
  background-image:
    radial-gradient(1100px 640px at 78% -10%, rgba(76, 141, 255, 0.16), transparent 62%),
    radial-gradient(860px 540px at 6% 2%, rgba(56, 225, 210, 0.10), transparent 60%),
    radial-gradient(900px 700px at 50% 118%, rgba(243, 196, 106, 0.05), transparent 65%);
  background-repeat: no-repeat;
  background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
}

/* 坐标网格叠加层：建立坐标感 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(233, 238, 250, 0.055) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(233, 238, 250, 0.055) 1px, transparent 1px);
  background-size: 96px 96px;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}

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

::selection {
  background: rgba(56, 225, 210, 0.28);
  color: #ffffff;
}

/* ---------- 内容主区与页脚：让出左右导轨 ---------- */
#main-content {
  position: relative;
  z-index: 1;
  padding-left: var(--rail-l);
  padding-right: var(--rail-r);
}

/* ==========================================================================
   1. skip link
   ========================================================================== */
.skip-link {
  position: fixed;
  top: 10px;
  left: 50%;
  z-index: 120;
  padding: 10px 20px;
  border-radius: 999px;
  background: var(--c-cyan);
  color: #04121a;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.02em;
  transform: translate(-50%, -180%);
  transition: transform 0.2s var(--ease);
}

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

/* ==========================================================================
   2. header / 顶栏 + 导轨
   ========================================================================== */
.site-header {
  position: relative;
  z-index: 60;
}

.frame-bar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 70;
  display: flex;
  align-items: center;
  gap: 20px;
  height: var(--bar-h);
  padding: 0 clamp(16px, 2.4vw, 32px);
  border-bottom: 1px solid var(--c-line);
  background: rgba(6, 10, 26, 0.82);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  backdrop-filter: blur(14px) saturate(140%);
}

/* --- 品牌 --- */
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 0 0 auto;
  padding: 6px 8px;
  border-radius: 10px;
}

.brand-mark {
  position: relative;
  flex: 0 0 auto;
  width: 26px;
  height: 26px;
  border: 1.5px solid var(--c-cyan);
  border-radius: 50%;
  box-shadow: inset 0 0 0 1px rgba(56, 225, 210, 0.18), 0 0 18px rgba(56, 225, 210, 0.32);
}

.brand-mark::before {
  content: "";
  position: absolute;
  inset: 6px;
  border-radius: 50%;
  background: var(--c-silver);
  opacity: 0.92;
}

.brand-mark::after {
  content: "";
  position: absolute;
  top: 50%;
  left: -6px;
  right: -6px;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--c-cyan), transparent);
  transform: rotate(-24deg);
}

.brand-text {
  display: flex;
  flex-direction: column;
  gap: 1px;
}

.brand-name {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 20px;
  line-height: 1.2;
  letter-spacing: 0.06em;
}

.brand-descriptor {
  font-size: 12px;
  line-height: 1.4;
  letter-spacing: 0.04em;
  color: var(--c-dust);
}

/* --- 状态面板（兼阅读进度刻度） --- */
.frame-status {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-left: auto;
  margin-right: auto;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--c-dust);
}

.status-dot {
  flex: 0 0 auto;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--c-cyan);
  box-shadow: 0 0 10px var(--c-cyan);
}

.frame-status-text { white-space: nowrap; }

.frame-status-meter {
  display: block;
  width: 128px;
  height: 2px;
  background: rgba(233, 238, 250, 0.16);
  overflow: hidden;
}

.frame-status-fill {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--c-cyan), var(--c-blue));
  transition: width 0.12s linear;
}

/* --- 移动端索引按钮 --- */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  margin-left: auto;
  padding: 8px 15px;
  border: 1px solid var(--c-line);
  border-radius: 999px;
  background: var(--c-glass);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  cursor: pointer;
  color: var(--c-silver);
}

.nav-toggle-label { line-height: 1; }

.nav-toggle-bars {
  position: relative;
  display: block;
  width: 16px;
  height: 2px;
  background: currentColor;
}

.nav-toggle-bars::before,
.nav-toggle-bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 16px;
  height: 2px;
  background: currentColor;
  transition: transform 0.2s var(--ease), opacity 0.2s var(--ease);
}

.nav-toggle-bars::before { top: -5px; }
.nav-toggle-bars::after { top: 5px; }

.nav-toggle[aria-expanded="true"] { border-color: var(--c-cyan); color: var(--c-cyan); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars { background: transparent; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::before { transform: translateY(5px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::after { transform: translateY(-5px) rotate(-45deg); }

/* --- 导轨 --- */
.frame-rail {
  position: fixed;
  top: var(--bar-h);
  bottom: 0;
  z-index: 65;
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding: 22px 18px 26px;
  overflow-y: auto;
  background: rgba(14, 21, 51, 0.72);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
}

.frame-rail--left {
  left: 0;
  width: var(--rail-l);
  border-right: 1px solid var(--c-line);
}

.frame-rail--right {
  right: 0;
  width: var(--rail-r);
  border-left: 1px solid var(--c-line);
}

.rail-label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--c-dust);
}

.rail-note {
  margin-top: auto;
  padding-top: 12px;
  border-top: 1px dashed rgba(233, 238, 250, 0.14);
  font-size: 11.5px;
  line-height: 1.7;
  color: var(--c-dust);
}

/* --- 类别索引 --- */
.index-list { display: flex; flex-direction: column; }

.index-item { border-top: 1px solid var(--c-line-soft); }
.index-item:last-child { border-bottom: 1px solid var(--c-line-soft); }

.index-link {
  position: relative;
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 11px 8px 11px 10px;
  border-left: 2px solid transparent;
  transition: background 0.18s var(--ease), border-color 0.18s var(--ease), color 0.18s var(--ease);
}

.index-link:hover {
  background: rgba(56, 225, 210, 0.07);
  border-left-color: var(--c-cyan);
}

.index-no {
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--c-dust);
  transition: color 0.18s var(--ease);
}

.index-name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 15px;
  letter-spacing: 0.02em;
}

.index-link[aria-current="page"] {
  border-left-color: var(--c-cyan);
  background: rgba(56, 225, 210, 0.09);
  color: var(--c-cyan);
}

.index-link[aria-current="page"] .index-no { color: var(--c-cyan); }

/* --- 快捷入口 --- */
.quick-list { display: grid; gap: 8px; }

.quick-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 11px 14px;
  border: 1px solid var(--c-line);
  border-radius: 10px;
  background: var(--c-glass);
  font-size: 14px;
  font-weight: 600;
  transition: border-color 0.18s var(--ease), background 0.18s var(--ease), color 0.18s var(--ease);
}

.quick-link::after {
  content: "↗";
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--c-cyan);
}

.quick-link:hover {
  border-color: var(--c-cyan);
  background: rgba(56, 225, 210, 0.09);
  color: var(--c-cyan);
}

/* --- 状态面板 --- */
.panel-status {
  display: grid;
  gap: 6px;
  padding: 14px;
  border: 1px solid var(--c-line);
  border-radius: 12px;
  background: rgba(23, 32, 73, 0.7);
}

.panel-status-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  line-height: 1.6;
}

.panel-status-key { color: var(--c-dust); }
.panel-status-value { color: var(--c-silver); }

/* ==========================================================================
   3. 通用排版与布局
   ========================================================================== */
.section {
  max-width: 1220px;
  margin-inline: auto;
  padding-block: clamp(48px, 6vw, 88px);
  padding-inline: clamp(18px, 2.6vw, 40px);
}

.section--tight { padding-block: clamp(28px, 3.4vw, 48px); }
.section--flush { padding-inline: 0; }

.section-title {
  font-size: clamp(26px, 3.2vw, 36px);
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.22em;
  color: var(--c-cyan);
}

.lede {
  max-width: 34em;
  font-size: 16.5px;
  line-height: 1.9;
  color: var(--c-dust);
}

.measure { max-width: 34em; }

.prose {
  max-width: 64em;
  font-size: 16px;
  line-height: 1.9;
  color: var(--c-body);
}

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

.prose h2 {
  margin-top: 1.8em;
  margin-bottom: 0.5em;
  font-size: clamp(20px, 2.2vw, 26px);
  color: var(--c-silver);
}

.prose h3 {
  margin-top: 1.5em;
  margin-bottom: 0.4em;
  font-size: 18px;
  color: var(--c-silver);
}

.prose ul, .prose ol {
  margin-top: 0.8em;
  display: grid;
  gap: 0.5em;
}

.prose li { padding-left: 1.2em; position: relative; }

.prose li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.85em;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  border: 1.5px solid var(--c-cyan);
}

.prose strong { color: var(--c-silver); font-weight: 700; }

.prose a { color: var(--c-cyan); border-bottom: 1px solid rgba(56, 225, 210, 0.4); }
.prose a:hover { border-bottom-color: var(--c-cyan); }

.divider {
  height: 1px;
  border: 0;
  background: linear-gradient(90deg, rgba(56, 225, 210, 0.55), rgba(233, 238, 250, 0.08) 32%, transparent);
}

/* 栏目页顶部固定更新行 */
.update-line {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 18px;
  padding: 10px 0;
  border-bottom: 1px solid rgba(233, 238, 250, 0.1);
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.6;
  letter-spacing: 0.04em;
  color: var(--c-dust);
}

.update-stamp { color: var(--c-gold); }

/* 键值表 */
.data-list {
  display: grid;
  border-top: 1px solid rgba(233, 238, 250, 0.1);
}

.data-row {
  display: grid;
  grid-template-columns: minmax(110px, 180px) 1fr;
  gap: 16px;
  padding: 14px 0;
  border-bottom: 1px solid rgba(233, 238, 250, 0.1);
}

.data-key {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--c-dust);
}

.data-value { font-size: 15px; line-height: 1.8; }

/* 时间轴 */
.timeline {
  position: relative;
  display: grid;
  gap: 24px;
  padding-left: 26px;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(180deg, var(--c-cyan), rgba(76, 141, 255, 0.5), transparent);
}

.timeline-item { position: relative; }

.timeline-item::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 9px;
  width: 11px;
  height: 11px;
  border: 1.5px solid var(--c-cyan);
  border-radius: 50%;
  background: var(--c-void);
  box-shadow: 0 0 0 4px rgba(56, 225, 210, 0.12);
}

.timeline-date {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--c-gold);
}

/* ==========================================================================
   4. 网格与卡片
   ========================================================================== */
.grid { display: grid; gap: 18px; }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }

.index-card {
  position: relative;
  display: block;
  padding: 20px 22px;
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  background: linear-gradient(180deg, rgba(23, 32, 73, 0.92), rgba(23, 32, 73, 0.7));
  transition: border-color 0.18s var(--ease), background 0.18s var(--ease);
}

.index-card::before {
  content: "";
  position: absolute;
  left: 0;
  top: 12px;
  bottom: 12px;
  width: 2px;
  background: var(--c-cyan);
  opacity: 0;
  transition: opacity 0.18s var(--ease);
}

.index-card--link:hover,
.index-card--link:focus-visible { border-color: var(--c-cyan); }

.index-card:hover::before,
.index-card:focus-visible::before { opacity: 1; }

/* 标签 */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  border: 1px solid rgba(233, 238, 250, 0.18);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  line-height: 1.6;
  letter-spacing: 0.06em;
  color: var(--c-dust);
  white-space: nowrap;
}

.tag--cyan {
  border-color: rgba(56, 225, 210, 0.45);
  background: rgba(56, 225, 210, 0.08);
  color: var(--c-cyan);
}

.tag--gold {
  border-color: rgba(184, 137, 47, 0.55);
  background: rgba(243, 196, 106, 0.08);
  color: var(--c-gold);
}

.tag--blue {
  border-color: rgba(76, 141, 255, 0.45);
  background: rgba(76, 141, 255, 0.1);
  color: var(--c-blue);
}

/* ==========================================================================
   5. 按钮
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 12px 22px;
  border: 1px solid transparent;
  border-radius: 999px;
  font-family: var(--font-body);
  font-size: 14.5px;
  font-weight: 700;
  letter-spacing: 0.02em;
  cursor: pointer;
  transition: border-color 0.18s var(--ease), background 0.18s var(--ease), color 0.18s var(--ease), filter 0.18s var(--ease);
}

.btn--primary {
  background: linear-gradient(120deg, var(--c-cyan), #6ef2e4 46%, var(--c-blue));
  color: #03121c;
  box-shadow: 0 10px 26px rgba(56, 225, 210, 0.2);
}

.btn--primary:hover { filter: brightness(1.07); }

.btn--ghost {
  border-color: rgba(233, 238, 250, 0.22);
  background: var(--c-glass);
  color: var(--c-silver);
}

.btn--ghost:hover {
  border-color: var(--c-cyan);
  background: rgba(56, 225, 210, 0.08);
  color: var(--c-cyan);
}

.btn--quiet {
  border-color: rgba(243, 196, 106, 0.42);
  background: rgba(243, 196, 106, 0.07);
  color: var(--c-gold);
}

.btn--quiet:hover {
  border-color: var(--c-gold);
  background: rgba(243, 196, 106, 0.14);
}

/* ==========================================================================
   6. 面包屑
   ========================================================================== */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--c-dust);
}

.breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.breadcrumb-item { display: inline-flex; align-items: center; gap: 8px; }

.breadcrumb-item + .breadcrumb-item::before {
  content: "/";
  color: rgba(155, 166, 198, 0.5);
}

.breadcrumb-item a:hover { color: var(--c-cyan); }

/* ==========================================================================
   7. 图片容器（页面阶段放置图片占位）
   ========================================================================== */
.media-frame {
  position: relative;
  overflow: hidden;
  border: 1px solid rgba(233, 238, 250, 0.14);
  border-radius: 16px;
  background-color: var(--c-indigo);
  background-image:
    radial-gradient(120% 90% at 18% 0%, rgba(76, 141, 255, 0.22), transparent 60%),
    radial-gradient(90% 80% at 92% 100%, rgba(56, 225, 210, 0.16), transparent 62%);
}

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(233, 238, 250, 0.07) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(233, 238, 250, 0.07) 1px, transparent 1px);
  background-size: 44px 44px;
}

.media-frame > img {
  position: relative;
  z-index: 1;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

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

.media-caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.6;
  color: var(--c-dust);
}

/* ==========================================================================
   8. 可展开内容组
   ========================================================================== */
.expand-group {
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  background: rgba(14, 21, 51, 0.72);
  overflow: hidden;
}

.expand-group + .expand-group { margin-top: 10px; }

.expand-trigger {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 18px;
  width: 100%;
  padding: 18px 20px;
  text-align: left;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 16px;
  line-height: 1.6;
  cursor: pointer;
  transition: background 0.18s var(--ease), color 0.18s var(--ease);
}

.expand-trigger:hover { background: rgba(56, 225, 210, 0.06); }
.expand-trigger[aria-expanded="true"] { color: var(--c-cyan); }

.expand-icon {
  position: relative;
  flex: 0 0 auto;
  width: 20px;
  height: 20px;
  margin-top: 3px;
}

.expand-icon::before,
.expand-icon::after {
  content: "";
  position: absolute;
  background: currentColor;
  border-radius: 1px;
}

.expand-icon::before { left: 0; right: 0; top: 9px; height: 1.5px; }

.expand-icon::after {
  top: 0;
  bottom: 0;
  left: 9px;
  width: 1.5px;
  transition: transform 0.2s var(--ease), opacity 0.2s var(--ease);
}

.expand-trigger[aria-expanded="true"] .expand-icon::after {
  transform: scaleY(0);
  opacity: 0;
}

.expand-panel {
  max-height: 0;
  overflow: hidden;
  visibility: hidden;
  opacity: 0;
  transition: max-height 0.22s var(--ease), opacity 0.22s var(--ease), visibility 0.22s var(--ease);
}

.expand-panel[data-open="true"] {
  visibility: visible;
  opacity: 1;
}

.expand-body {
  padding: 0 20px 20px;
  font-size: 15.5px;
  line-height: 1.9;
  color: var(--c-body);
}

/* ==========================================================================
   9. 类型筛选
   ========================================================================== */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
}

.filter-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  border: 1px solid rgba(233, 238, 250, 0.18);
  border-radius: 999px;
  background: var(--c-glass);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--c-dust);
  cursor: pointer;
  transition: border-color 0.18s var(--ease), background 0.18s var(--ease), color 0.18s var(--ease);
}

.filter-chip:hover {
  border-color: var(--c-blue);
  color: var(--c-silver);
}

.filter-chip[aria-pressed="true"] {
  border-color: var(--c-cyan);
  background: rgba(56, 225, 210, 0.14);
  color: var(--c-cyan);
}

.filter-count { opacity: 0.72; }

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

/* ==========================================================================
   10. 显现动效
   ========================================================================== */
[data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease);
}

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

/* ==========================================================================
   11. footer
   ========================================================================== */
.site-footer {
  position: relative;
  z-index: 1;
  margin-top: clamp(48px, 6vw, 96px);
  padding: 56px var(--rail-r) 40px var(--rail-l);
  border-top: 1px solid rgba(233, 238, 250, 0.1);
  background: linear-gradient(180deg, rgba(14, 21, 51, 0.55), var(--c-indigo));
}

.footer-inner {
  max-width: 1220px;
  margin-inline: auto;
  padding-inline: clamp(18px, 2.6vw, 40px);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1.6fr;
  gap: 32px;
}

.footer-brand-name {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 22px;
  letter-spacing: 0.08em;
}

.footer-brand-desc {
  margin-top: 6px;
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--c-dust);
}

.footer-closing {
  margin-top: 18px;
  max-width: 20em;
  font-size: 14px;
  line-height: 1.9;
  color: var(--c-body);
  border-left: 2px solid var(--c-cyan);
  padding-left: 12px;
}

.footer-col-title {
  margin-bottom: 14px;
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--c-dust);
}

.footer-links {
  display: grid;
  gap: 9px;
  font-size: 14.5px;
}

.footer-links a {
  display: inline-block;
  color: var(--c-body);
  transition: color 0.18s var(--ease);
}

.footer-links a:hover {
  color: var(--c-cyan);
  text-decoration: underline;
  text-underline-offset: 4px;
}

.contact-list {
  display: grid;
  gap: 16px;
}

.contact-item {
  display: grid;
  gap: 4px;
  justify-items: start;
}

.contact-label {
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--c-dust);
}

.contact-line {
  font-size: 13px;
  line-height: 1.7;
  color: var(--c-silver);
  word-break: break-word;
}

.copy-btn {
  margin-top: 6px;
  padding: 4px 12px;
  border: 1px solid rgba(233, 238, 250, 0.2);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--c-dust);
  cursor: pointer;
  transition: border-color 0.18s var(--ease), color 0.18s var(--ease), background 0.18s var(--ease);
}

.copy-btn:hover {
  border-color: var(--c-cyan);
  color: var(--c-cyan);
}

.copy-btn[data-copied="true"] {
  border-color: var(--c-gold);
  background: rgba(243, 196, 106, 0.1);
  color: var(--c-gold);
}

.contact-note {
  margin-top: 16px;
  max-width: 26em;
  font-size: 12.5px;
  line-height: 1.8;
  color: var(--c-dust);
}

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 22px;
  margin-top: 44px;
  padding-top: 20px;
  border-top: 1px solid rgba(233, 238, 250, 0.1);
}

.footer-meta-line {
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--c-dust);
}

.footer-legal {
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--c-gold);
}

.to-top {
  margin-left: auto;
  padding: 8px 16px;
  border: 1px solid rgba(233, 238, 250, 0.2);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: var(--c-dust);
  cursor: pointer;
  transition: border-color 0.18s var(--ease), color 0.18s var(--ease);
}

.to-top:hover {
  border-color: var(--c-cyan);
  color: var(--c-cyan);
}

/* ==========================================================================
   12. 断点
   ========================================================================== */
@media (max-width: 1279px) {
  :root {
    --rail-l: 210px;
    --rail-r: 252px;
  }

  .footer-grid { grid-template-columns: 1.4fr 1fr 1fr 1.5fr; gap: 24px; }
}

@media (max-width: 1023px) {
  :root {
    --rail-l: 0px;
    --rail-r: 0px;
  }

  .nav-toggle { display: inline-flex; }
  .frame-status { display: none; }

  .frame-body {
    position: fixed;
    top: var(--bar-h);
    left: 0;
    right: 0;
    z-index: 66;
    display: grid;
    gap: 0;
    max-height: calc(100vh - var(--bar-h));
    padding: 18px clamp(16px, 4vw, 28px) 26px;
    overflow-y: auto;
    border-bottom: 1px solid var(--c-line);
    background: rgba(6, 10, 26, 0.96);
    -webkit-backdrop-filter: blur(16px);
    backdrop-filter: blur(16px);
    visibility: hidden;
    opacity: 0;
    transform: translateY(-10px);
    transition: opacity 0.22s var(--ease), transform 0.22s var(--ease), visibility 0.22s var(--ease);
  }

  .frame-body[data-open="true"] {
    visibility: visible;
    opacity: 1;
    transform: none;
  }

  .frame-rail {
    position: static;
    top: auto;
    bottom: auto;
    left: auto;
    right: auto;
    width: auto;
    padding: 0;
    overflow: visible;
    border: 0;
    background: none;
    -webkit-backdrop-filter: none;
    backdrop-filter: none;
  }

  .frame-rail--right { margin-top: 22px; }

  .rail-note { margin-top: 14px; }

  body.nav-open { overflow: hidden; }

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

  .footer-grid { grid-template-columns: 1fr 1fr; gap: 28px; }

  .footer-col--contact { grid-column: 1 / -1; }
}

@media (max-width: 640px) {
  .brand-descriptor { display: none; }

  .grid--2,
  .grid--3 { grid-template-columns: 1fr; }

  .footer-grid { grid-template-columns: 1fr; }

  .data-row { grid-template-columns: 1fr; gap: 4px; }

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

  .to-top { margin-left: 0; }
}

/* ==========================================================================
   13. 无障碍：减少动态效果
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }

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

  .frame-status-fill { transition: none; }
}