/* ============================================================
   银河官网3868 · /assets/site.css
   共享外壳：reset / 变量 / 中文排版 / 头部 / 页脚 / 基础组件
   ============================================================ */

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

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

ul,
ol { list-style: none; }

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

button,
input,
select,
textarea { font: inherit; color: inherit; }

button { background: none; border: 0; cursor: pointer; }

/* ---------- 2. 变量 ---------- */
:root {
  --void: #070B1B;
  --nebula: #0E1530;
  --indigo: #4B2E9E;
  --galaxy: #7B4DFF;
  --cyan: #35E0D0;
  --gold: #F2C063;
  --wine: #8C2B4A;
  --teal: #0B3B3C;
  --ink: #E8ECF7;
  --muted: #9AA6C4;

  --line: rgba(154, 166, 196, 0.20);
  --line-mid: rgba(154, 166, 196, 0.36);
  --line-cyan: rgba(53, 224, 208, 0.45);
  --line-galaxy: rgba(123, 77, 255, 0.42);

  --fs-1: clamp(40px, 5.4vw, 64px);
  --fs-2: clamp(32px, 4.2vw, 48px);
  --fs-3: clamp(26px, 3vw, 38px);
  --fs-4: clamp(22px, 2.4vw, 30px);
  --fs-5: 22px;
  --fs-6: 18px;
  --fs-7: 16px;
  --fs-8: 13px;

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

  --shell: min(1240px, 92vw);
  --nav-break: 900px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

/* ---------- 3. 基础与中文排版 ---------- */
html {
  -webkit-text-size-adjust: 100%;
  scroll-padding-top: 168px;
}

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

body {
  min-height: 100vh;
  background-color: var(--void);
  background-image:
    radial-gradient(960px 540px at 10% -8%, rgba(123, 77, 255, 0.20), transparent 62%),
    radial-gradient(780px 460px at 92% 2%, rgba(53, 224, 208, 0.12), transparent 60%),
    radial-gradient(1200px 720px at 46% 112%, rgba(75, 46, 158, 0.20), transparent 66%);
  background-repeat: no-repeat;
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: var(--fs-6);
  font-weight: 400;
  line-height: 1.8;
  letter-spacing: 0.01em;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    repeating-linear-gradient(90deg, rgba(154, 166, 196, 0.055) 0 1px, transparent 1px 96px),
    repeating-linear-gradient(0deg, rgba(154, 166, 196, 0.055) 0 1px, transparent 1px 96px);
  -webkit-mask-image: radial-gradient(circle at 50% 26%, #000 0%, transparent 78%);
  mask-image: radial-gradient(circle at 50% 26%, #000 0%, transparent 78%);
}

#main-content {
  position: relative;
  z-index: 1;
  display: block;
}

h1,
h2,
h3,
h4 {
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -0.01em;
}

h1 { font-size: var(--fs-1); }
h2 { font-size: var(--fs-3); }
h3 { font-size: var(--fs-4); }
h4 { font-size: var(--fs-5); }

p { line-height: 1.8; }

a { color: var(--cyan); text-decoration: none; }
a:hover { color: var(--gold); }

::selection { background: rgba(123, 77, 255, 0.55); color: #fff; }

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

/* ---------- 4. 工具类 ---------- */
.mono { font-family: var(--font-mono); letter-spacing: 0.04em; }
.text-muted { color: var(--muted); }
.text-cyan { color: var(--cyan); }
.text-gold { color: var(--gold); }

.container {
  position: relative;
  width: var(--shell);
  margin-inline: auto;
}

.section { padding: 88px 0; position: relative; }
.section--tight { padding: 56px 0; }

.rule {
  height: 1px;
  border: 0;
  background: var(--line);
  margin: 0;
}

.section-head {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-width: 780px;
  margin-bottom: 40px;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--cyan);
  letter-spacing: 0.2em;
  text-transform: uppercase;
}

.eyebrow::before {
  content: "";
  width: 30px;
  height: 1px;
  background: var(--cyan);
  flex: 0 0 auto;
}

.section-title {
  margin: 0;
  font-size: var(--fs-3);
  font-weight: 800;
}

.section-note {
  margin: 0;
  color: var(--muted);
  font-size: var(--fs-7);
}

.prose { max-width: 68ch; }
.prose p { margin: 0 0 1.1em; }
.prose h2,
.prose h3 { margin: 1.8em 0 0.6em; }
.prose ul { list-style: disc; padding-left: 1.3em; }
.prose ol { list-style: decimal; padding-left: 1.3em; }
.prose li { margin: 0.35em 0; }
.prose strong { color: var(--gold); }

/* ---------- 5. 布局骨架 ---------- */
.split {
  display: grid;
  grid-template-columns: minmax(230px, 1fr) minmax(0, 2fr);
  gap: 56px;
  align-items: start;
}

.grid { display: grid; gap: 24px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }

/* ---------- 6. 组件 ---------- */
.card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 28px 26px 26px;
  background: var(--nebula);
  border: 1px solid var(--line);
  transition: border-color 0.22s var(--ease), background-color 0.22s var(--ease), transform 0.22s var(--ease);
}

.card::after {
  content: "";
  position: absolute;
  top: -1px;
  left: -1px;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--galaxy), var(--cyan));
  transition: width 0.3s var(--ease);
}

.card:hover {
  border-color: var(--line-cyan);
  background: #111A3A;
  transform: translateY(-4px);
}

.card:hover::after { width: calc(100% + 2px); }

.card-tag {
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--cyan);
  letter-spacing: 0.16em;
}

.card-title { margin: 0; font-size: var(--fs-5); font-weight: 700; }

.card-desc {
  margin: 0;
  color: var(--muted);
  font-size: var(--fs-7);
  line-height: 1.8;
}

.panel {
  position: relative;
  padding: 36px;
  background: var(--nebula);
  border: 1px solid var(--line);
}

.panel--indigo { background: linear-gradient(158deg, rgba(75, 46, 158, 0.55), rgba(14, 21, 48, 0.94) 68%); }
.panel--teal { background: linear-gradient(158deg, rgba(11, 59, 60, 0.86), rgba(14, 21, 48, 0.94) 68%); }
.panel--wine { background: linear-gradient(158deg, rgba(140, 43, 74, 0.50), rgba(14, 21, 48, 0.94) 68%); }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 13px 26px;
  font-size: var(--fs-7);
  font-weight: 700;
  letter-spacing: 0.06em;
  border: 1px solid transparent;
  transition: background-color 0.2s var(--ease), color 0.2s var(--ease), border-color 0.2s var(--ease), box-shadow 0.2s var(--ease);
}

.btn-primary {
  background: var(--gold);
  border-color: var(--gold);
  color: var(--void);
}

.btn-primary:hover {
  background: #FFD98A;
  color: var(--void);
  box-shadow: 0 0 0 4px rgba(242, 192, 99, 0.16);
}

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

.btn-ghost:hover {
  border-color: var(--cyan);
  background: rgba(53, 224, 208, 0.08);
  color: var(--cyan);
}

.tag {
  display: inline-block;
  padding: 4px 10px;
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  letter-spacing: 0.1em;
  color: var(--cyan);
  border: 1px solid var(--line-cyan);
  background: rgba(53, 224, 208, 0.07);
}

.tag--gold {
  color: var(--gold);
  border-color: rgba(242, 192, 99, 0.42);
  background: rgba(242, 192, 99, 0.08);
}

.ledger {
  border-top: 1px solid var(--line);
}

.ledger li {
  display: flex;
  align-items: baseline;
  gap: 16px;
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
  font-size: var(--fs-7);
}

.ledger li::before {
  content: attr(data-index);
  flex: 0 0 auto;
  min-width: 42px;
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--cyan);
  letter-spacing: 0.08em;
}

.steps {
  counter-reset: step;
  border-top: 1px solid var(--line);
}

.step {
  position: relative;
  counter-increment: step;
  padding: 22px 0 22px 62px;
  border-bottom: 1px solid var(--line);
}

.step::before {
  content: counter(step, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 24px;
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--gold);
  letter-spacing: 0.1em;
}

.step-title {
  margin: 0;
  font-size: var(--fs-6);
  font-weight: 700;
}

.step-desc {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: var(--fs-7);
}

.chapter-rail {
  position: sticky;
  top: 168px;
  align-self: start;
  padding-left: 18px;
  border-left: 1px solid var(--line);
}

.chapter-rail-title {
  margin: 0 0 16px;
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--gold);
  letter-spacing: 0.18em;
}

.rail-list { display: grid; gap: 2px; }

.rail-link {
  display: block;
  padding: 9px 12px 9px 14px;
  border-left: 2px solid transparent;
  color: var(--muted);
  font-size: var(--fs-7);
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease), background-color 0.2s var(--ease);
}

.rail-link:hover {
  color: var(--ink);
  background: rgba(123, 77, 255, 0.12);
}

.rail-link[aria-current="true"] {
  color: var(--cyan);
  border-left-color: var(--cyan);
  background: rgba(53, 224, 208, 0.07);
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--muted);
  letter-spacing: 0.06em;
}

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

.breadcrumb li + li::before {
  content: "/";
  color: rgba(154, 166, 196, 0.5);
}

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

.media-frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  border: 1px solid var(--line);
  background:
    radial-gradient(120% 90% at 12% 8%, rgba(123, 77, 255, 0.28), transparent 62%),
    radial-gradient(120% 90% at 88% 90%, rgba(53, 224, 208, 0.16), transparent 60%),
    linear-gradient(150deg, #0E1530, #121A38 58%, #0B3B3C);
}

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

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(180deg, transparent 55%, rgba(7, 11, 27, 0.55));
}

.media-frame--plain::after { display: none; }
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--tall { aspect-ratio: 3 / 4; }

.media-caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--muted);
  letter-spacing: 0.06em;
}

/* ---------- 7. 头部 ---------- */
.skip-link {
  position: absolute;
  top: -80px;
  left: 16px;
  z-index: 200;
  padding: 10px 20px;
  background: var(--gold);
  color: var(--void);
  font-size: var(--fs-8);
  font-weight: 700;
  letter-spacing: 0.14em;
  transition: top 0.18s var(--ease);
}

.skip-link:focus { top: 12px; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 90;
  background: linear-gradient(180deg, rgba(7, 11, 27, 0.97), rgba(7, 11, 27, 0.88));
  border-bottom: 1px solid var(--line-mid);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
}

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

.header-track {
  position: relative;
  border-bottom: 1px solid var(--line-galaxy);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  width: var(--shell);
  margin-inline: auto;
}

.header-rail .header-inner {
  min-height: 66px;
  padding: 10px 0;
  transition: min-height 0.22s var(--ease), padding 0.22s var(--ease);
}

.header-track .header-inner {
  min-height: 58px;
  padding: 0;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 14px;
  color: var(--ink);
}

.brand:hover { color: var(--ink); }

.brand-mark {
  position: relative;
  padding-left: 18px;
  font-size: var(--fs-5);
  font-weight: 800;
  letter-spacing: 0.06em;
}

.brand-mark::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  width: 8px;
  height: 8px;
  background: var(--gold);
  transform: translateY(-50%) rotate(45deg);
}

.brand-tagline {
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--muted);
  letter-spacing: 0.1em;
}

.header-utility {
  display: flex;
  align-items: center;
  gap: 24px;
}

.header-coord {
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--cyan);
  letter-spacing: 0.14em;
}

.utility-nav { display: flex; gap: 20px; }

.utility-nav a {
  padding-bottom: 3px;
  color: var(--muted);
  font-size: var(--fs-8);
  letter-spacing: 0.08em;
  border-bottom: 1px solid transparent;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.utility-nav a:hover {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

.primary-nav { flex: 1 1 auto; }

.primary-nav ul {
  display: flex;
  align-items: stretch;
  counter-reset: navidx;
}

.primary-nav li {
  display: flex;
  counter-increment: navidx;
}

.primary-nav a {
  position: relative;
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 18px 17px;
  border-right: 1px solid var(--line);
  color: var(--ink);
  font-size: var(--fs-7);
  font-weight: 600;
  letter-spacing: 0.05em;
  transition: color 0.2s var(--ease), background-color 0.2s var(--ease), padding 0.22s var(--ease);
}

.primary-nav li:first-child a { border-left: 1px solid var(--line); }

.primary-nav a::before {
  content: counter(navidx, decimal-leading-zero);
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  font-weight: 400;
  color: var(--cyan);
  opacity: 0.78;
}

.primary-nav a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  background: var(--cyan);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.24s var(--ease);
}

.primary-nav a:hover {
  background: rgba(123, 77, 255, 0.16);
  color: #FFFFFF;
}

.primary-nav a:hover::after { transform: scaleX(1); }

.primary-nav a[aria-current="page"] {
  color: var(--gold);
  background: rgba(242, 192, 99, 0.08);
}

.primary-nav a[aria-current="page"]::after {
  transform: scaleX(1);
  background: var(--gold);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  padding: 9px 14px;
  border: 1px solid var(--line-mid);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  letter-spacing: 0.12em;
  transition: border-color 0.2s var(--ease), color 0.2s var(--ease);
}

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

.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: 100%;
  height: 1.5px;
  background: var(--cyan);
  transition: transform 0.22s var(--ease), top 0.22s var(--ease);
}

.nav-toggle-bars::before { top: 0; }
.nav-toggle-bars::after { top: 10px; }

.nav-toggle[aria-expanded="true"] .nav-toggle-bars::before { top: 5px; transform: rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::after { top: 5px; transform: rotate(-45deg); }

.nav-toggle-text { white-space: nowrap; }

.header-cta {
  margin-left: 22px;
  padding: 11px 22px;
  background: var(--gold);
  border: 1px solid var(--gold);
  color: var(--void);
  font-size: var(--fs-8);
  font-weight: 700;
  letter-spacing: 0.1em;
  white-space: nowrap;
  transition: background-color 0.2s var(--ease), box-shadow 0.2s var(--ease);
}

.header-cta:hover {
  background: #FFD98A;
  color: var(--void);
  box-shadow: 0 0 0 4px rgba(242, 192, 99, 0.16);
}

/* 滚动后压缩为细条 */
.site-header[data-scrolled="true"] .header-rail .header-inner {
  min-height: 46px;
  padding: 4px 0;
}

.site-header[data-scrolled="true"] .brand-tagline { display: none; }

.site-header[data-scrolled="true"] .primary-nav a { padding-top: 12px; padding-bottom: 12px; }

/* ---------- 8. 页脚 ---------- */
.site-footer {
  position: relative;
  z-index: 2;
  margin-top: 96px;
  background: linear-gradient(180deg, #0E1530 0%, #070B1B 68%);
  border-top: 1px solid var(--line-galaxy);
  color: var(--ink);
}

.footer-track {
  height: 2px;
  background: linear-gradient(90deg, var(--indigo), var(--galaxy) 26%, var(--cyan) 52%, var(--gold) 74%, var(--wine) 88%, var(--teal));
}

.footer-inner {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 2fr) minmax(0, 1.35fr);
  gap: 48px 40px;
  width: var(--shell);
  margin-inline: auto;
  padding: 64px 0 44px;
}

.footer-mark {
  margin: 0 0 12px;
  font-size: var(--fs-5);
  font-weight: 800;
  letter-spacing: 0.05em;
}

.footer-signature {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--muted);
  letter-spacing: 0.06em;
}

.footer-coord {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--cyan);
  letter-spacing: 0.12em;
}

.footer-columns {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 28px;
}

.footer-col-title,
.footer-contact-title {
  margin: 0 0 16px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  font-weight: 400;
  color: var(--gold);
  letter-spacing: 0.16em;
}

.footer-links {
  display: grid;
  gap: 10px;
}

.footer-links a {
  position: relative;
  display: inline-block;
  padding-left: 16px;
  color: var(--muted);
  font-size: var(--fs-7);
  transition: color 0.2s var(--ease);
}

.footer-links a::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.85em;
  width: 7px;
  height: 1px;
  background: var(--muted);
  transition: width 0.2s var(--ease), background-color 0.2s var(--ease);
}

.footer-links a:hover { color: var(--cyan); }

.footer-links a:hover::before {
  width: 11px;
  background: var(--cyan);
}

.footer-line {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
  margin: 0 0 12px;
  font-size: var(--fs-8);
}

.footer-label {
  flex: 0 0 auto;
  min-width: 62px;
  color: var(--muted);
  font-family: var(--font-mono);
  letter-spacing: 0.1em;
}

.footer-value {
  font-family: var(--font-mono);
  color: var(--ink);
  letter-spacing: 0.02em;
  word-break: break-all;
}

.copy-btn {
  padding: 3px 9px;
  border: 1px solid var(--line-mid);
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  letter-spacing: 0.08em;
  transition: border-color 0.2s var(--ease), background-color 0.2s var(--ease), color 0.2s var(--ease);
}

.copy-btn:hover {
  border-color: var(--cyan);
  background: rgba(53, 224, 208, 0.1);
}

.copy-btn[data-copied="true"] {
  border-color: var(--gold);
  color: var(--gold);
  background: rgba(242, 192, 99, 0.1);
}

.footer-base {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px 28px;
  width: var(--shell);
  margin-inline: auto;
  padding: 22px 0 44px;
  border-top: 1px solid var(--line);
}

.footer-icp,
.footer-copy {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  color: var(--muted);
  letter-spacing: 0.08em;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
}

.footer-legal a {
  color: var(--muted);
  font-size: var(--fs-8);
  letter-spacing: 0.06em;
}

.footer-legal a:hover { color: var(--cyan); }

/* ---------- 9. 进度条 / 返回顶部 / 显现 ---------- */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  z-index: 200;
  pointer-events: none;
  background: rgba(154, 166, 196, 0.12);
}

.progress-fill {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--galaxy), var(--cyan) 62%, var(--gold));
}

.back-to-top {
  position: fixed;
  right: clamp(16px, 3vw, 40px);
  bottom: clamp(16px, 3vw, 36px);
  z-index: 120;
  padding: 12px 16px;
  background: rgba(14, 21, 48, 0.94);
  border: 1px solid var(--line-mid);
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: var(--fs-8);
  letter-spacing: 0.12em;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 0.22s var(--ease), transform 0.22s var(--ease), visibility 0.22s linear, border-color 0.2s var(--ease);
}

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

.back-to-top:hover {
  border-color: var(--cyan);
  background: rgba(53, 224, 208, 0.12);
}

.reveal { opacity: 1; transform: none; }

html.js .reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease);
  transition-delay: var(--reveal-delay, 0ms);
}

html.js .reveal.is-visible {
  opacity: 1;
  transform: none;
}

/* ---------- 10. 响应式 ---------- */
@media (max-width: 1080px) {
  .footer-inner {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  }
  .footer-brand { grid-column: 1 / -1; }
}

@media (max-width: 1024px) {
  .split { grid-template-columns: 1fr; gap: 32px; }
  .chapter-rail {
    position: static;
    border-left: 0;
    padding-left: 0;
  }
  .grid-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 900px) {
  html { scroll-padding-top: 128px; }

  .section { padding: 64px 0; }
  .section--tight { padding: 44px 0; }

  .nav-toggle { display: inline-flex; }

  .header-rail .header-inner { min-height: 58px; padding: 10px 0; }
  .brand-tagline,
  .header-coord,
  .utility-nav { display: none; }

  .header-track .header-inner { min-height: 54px; }

  .primary-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    max-height: 0;
    overflow: hidden;
    background: rgba(7, 11, 27, 0.985);
    border-bottom: 1px solid var(--line-cyan);
    transition: max-height 0.3s var(--ease);
  }

  .primary-nav[data-open="true"] {
    max-height: min(74vh, 560px);
    overflow-y: auto;
  }

  .primary-nav ul {
    flex-direction: column;
    align-items: stretch;
    padding: 6px 0;
  }

  .primary-nav li { width: 100%; }

  .primary-nav a {
    padding: 16px 4vw;
    border-right: 0;
    border-bottom: 1px solid var(--line);
    font-size: var(--fs-6);
  }

  .primary-nav li:first-child a { border-left: 0; }

  .primary-nav a::after { display: none; }

  .header-cta { margin-left: auto; padding: 10px 16px; }

  .site-header[data-scrolled="true"] .primary-nav a { padding-top: 16px; padding-bottom: 16px; }
}

@media (max-width: 720px) {
  body { font-size: var(--fs-6); }

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

  .footer-inner {
    grid-template-columns: 1fr;
    gap: 36px;
    padding: 48px 0 32px;
  }
  .footer-brand { grid-column: auto; }
  .footer-columns { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-base { padding: 20px 0 40px; }
  .panel { padding: 26px 22px; }
  .step { padding-left: 50px; }
}

@media (max-width: 520px) {
  .header-cta { display: none; }
  .footer-columns { grid-template-columns: 1fr; }
  .footer-legal { gap: 14px; }
}

/* ---------- 11. 动效偏好 ---------- */
@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;
  }

  html.js .reveal {
    opacity: 1;
    transform: none;
  }

  .card:hover { transform: none; }
}