/* ============================================================
   天辰登陆指南 · /assets/site.css
   共享外壳 / 变量 / 通用组件 / 响应式
   ============================================================ */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 24px;
}

body,
h1, h2, h3, h4, h5, h6,
p, ul, ol, dl, dd, figure, blockquote, pre {
  margin: 0;
}

ul, ol { padding: 0; list-style: none; }

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

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

a { color: inherit; }

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

[hidden] { display: none !important; }

/* ---------- 2. 变量 ---------- */
:root {
  --ink: #0E2A3F;
  --ink-deep: #081C29;
  --ink-soft: #1D4258;
  --paper: #F6F1E7;
  --paper-2: #EAE2D3;
  --amber: #D98A2B;
  --amber-2: #F2C98A;
  --celadon: #3E7C6A;
  --coral: #B4453A;
  --graphite: #2B2F33;
  --mist: #7A8791;
  --white: #FFFFFF;

  --line: rgba(14, 42, 63, 0.16);
  --line-strong: rgba(14, 42, 63, 0.32);
  --line-light: rgba(246, 241, 231, 0.16);

  --font-sans: "Noto Sans SC", "Source Han Sans SC", "Source Han Sans CN",
               "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
               system-ui, -apple-system, sans-serif;
  --font-mono: ui-monospace, "IBM Plex Mono", "SFMono-Regular", Menlo,
               Consolas, "Liberation Mono", monospace;

  --page: 1264px;
  --gutter: 24px;
  --dur: 180ms;
  --dur-mid: 260ms;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

/* ---------- 3. 中文排版基础 ---------- */
body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.8;
  letter-spacing: 0.01em;
  color: var(--graphite);
  background-color: var(--paper);
  background-image:
    linear-gradient(to right, rgba(14, 42, 63, 0.055) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(14, 42, 63, 0.055) 1px, transparent 1px);
  background-size: 48px 48px;
  background-position: -1px -1px;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6 {
  color: var(--ink);
  font-weight: 900;
  line-height: 1.14;
  letter-spacing: 0.04em;
  text-wrap: balance;
}

p { text-wrap: pretty; }

a {
  text-decoration-thickness: 1px;
  text-underline-offset: 4px;
}

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

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

/* ---------- 4. 布局骨架 ---------- */
.shell {
  width: 100%;
  max-width: var(--page);
  margin-inline: auto;
  padding-inline: clamp(18px, 4vw, 56px);
}

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}

.bento {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}

/* ---------- 5. skip link ---------- */
.skip-link {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 200;
  transform: translateY(-130%);
  padding: 0.7rem 1.1rem;
  background: var(--amber);
  color: var(--ink-deep);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-decoration: none;
  transition: transform var(--dur) var(--ease);
}

.skip-link:focus {
  transform: translateY(0);
  outline: 2px solid var(--ink);
  outline-offset: -4px;
}

/* ---------- 6. 头部:状态刻度条 ---------- */
.site-header {
  position: relative;
  z-index: 50;
}

.utility-bar {
  background: var(--ink-deep);
  color: rgba(246, 241, 231, 0.72);
  font-size: 12px;
  letter-spacing: 0.12em;
  border-bottom: 1px solid rgba(246, 241, 231, 0.08);
}

.utility-bar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: 36px;
  padding-block: 4px;
}

.utility-bar__status {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: rgba(246, 241, 231, 0.78);
}

.status-dot {
  width: 7px;
  height: 7px;
  flex: none;
  border-radius: 50%;
  background: var(--celadon);
  box-shadow: 0 0 0 3px rgba(62, 124, 106, 0.24);
}

.utility-bar__sep {
  color: rgba(246, 241, 231, 0.32);
}

.utility-bar__list {
  display: flex;
  align-items: center;
  gap: 1.35rem;
  flex: none;
}

.utility-bar__list a {
  text-decoration: none;
  color: rgba(246, 241, 231, 0.74);
  border-bottom: 1px solid transparent;
  padding-bottom: 1px;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.utility-bar__list a:hover {
  color: var(--amber-2);
  border-bottom-color: var(--amber-2);
}

/* ---------- 7. 头部:命令栏 ---------- */
.command-bar {
  background: var(--ink);
  color: var(--paper);
  border-bottom: 1px solid var(--line-light);
}

.command-bar__inner {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  min-height: 74px;
  padding-block: 12px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  flex: none;
  text-decoration: none;
  color: var(--paper);
}

.brand__mark {
  position: relative;
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border: 1px solid var(--amber);
  color: var(--amber-2);
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.04em;
}

.brand__mark::after {
  content: "";
  position: absolute;
  inset: 4px;
  border: 1px solid rgba(217, 138, 43, 0.3);
  pointer-events: none;
}

.brand__text {
  display: grid;
  gap: 1px;
  line-height: 1.2;
}

.brand__name {
  font-size: 16px;
  font-weight: 900;
  letter-spacing: 0.09em;
}

.brand__tagline {
  font-size: 11px;
  letter-spacing: 0.14em;
  color: rgba(246, 241, 231, 0.58);
}

.site-nav {
  margin-inline: auto;
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: clamp(2px, 0.8vw, 12px);
}

.site-nav__link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 0.4em;
  padding: 0.45rem 0.55rem;
  font-size: 13.5px;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: rgba(246, 241, 231, 0.76);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  transition: color var(--dur) var(--ease),
              background-color var(--dur) var(--ease),
              border-color var(--dur) var(--ease);
}

.site-nav__index {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.08em;
  color: rgba(242, 201, 138, 0.5);
  transition: color var(--dur) var(--ease);
}

.site-nav__link:hover {
  color: var(--paper);
  background: rgba(246, 241, 231, 0.07);
}

.site-nav__link:hover .site-nav__index {
  color: var(--amber-2);
}

.site-nav__link[aria-current="page"] {
  color: var(--paper);
  border-bottom-color: var(--amber);
  background: rgba(246, 241, 231, 0.06);
}

.site-nav__link[aria-current="page"] .site-nav__index {
  color: var(--amber);
}

/* ---------- 8. 头部:命令过滤 ---------- */
.command {
  position: relative;
  flex: 1 1 190px;
  max-width: 300px;
  margin-left: auto;
}

.command__label {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  white-space: nowrap;
  clip-path: inset(50%);
}

.command__input {
  width: 100%;
  padding: 0.55rem 0.75rem;
  font-family: var(--font-sans);
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--paper);
  background: rgba(246, 241, 231, 0.08);
  border: 1px solid rgba(246, 241, 231, 0.24);
  border-radius: 0;
  -webkit-appearance: none;
  appearance: none;
  transition: background-color var(--dur) var(--ease),
              border-color var(--dur) var(--ease);
}

.command__input::placeholder {
  color: rgba(246, 241, 231, 0.46);
}

.command__input:hover {
  border-color: rgba(246, 241, 231, 0.42);
}

.command__input:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 1px;
  background: rgba(246, 241, 231, 0.14);
  border-color: var(--amber);
}

.command__results {
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  right: 0;
  z-index: 60;
  max-height: 340px;
  overflow: auto;
  background: var(--white);
  border: 1px solid var(--ink);
  box-shadow: 6px 6px 0 rgba(14, 42, 63, 0.12);
}

.command__results[hidden] {
  display: none;
}

.command__result {
  display: grid;
  gap: 1px;
  padding: 0.7rem 0.85rem;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  transition: background-color var(--dur) var(--ease),
              box-shadow var(--dur) var(--ease);
}

.command__result:last-child {
  border-bottom: 0;
}

.command__result:hover,
.command__result:focus-visible {
  background: var(--paper-2);
  box-shadow: inset 2px 0 0 var(--amber);
  outline: none;
}

.command__result-title {
  font-size: 13.5px;
  font-weight: 700;
  letter-spacing: 0.05em;
}

.command__result-meta {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--mist);
}

.command__empty {
  padding: 0.8rem 0.85rem;
  font-size: 12.5px;
  line-height: 1.7;
  letter-spacing: 0.04em;
  color: var(--mist);
}

/* ---------- 9. 头部:移动导航按钮 ---------- */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 0.75rem;
  border: 1px solid rgba(246, 241, 231, 0.3);
  color: var(--paper);
  font-size: 12px;
  letter-spacing: 0.14em;
  cursor: pointer;
  transition: border-color var(--dur) var(--ease),
              background-color var(--dur) var(--ease);
}

.nav-toggle:hover {
  border-color: var(--amber);
  background: rgba(246, 241, 231, 0.08);
}

.nav-toggle__bars {
  position: relative;
  display: block;
  width: 16px;
  height: 10px;
}

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 16px;
  height: 1.5px;
  background: var(--paper);
  transition: transform var(--dur) var(--ease);
}

.nav-toggle__bars::before { top: 0; }
.nav-toggle__bars::after { bottom: 0; }

.nav-toggle[aria-expanded="true"] {
  border-color: var(--amber);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before {
  transform: translateY(4.25px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after {
  transform: translateY(-4.25px) rotate(-45deg);
}

.nav-toggle__text {
  font-weight: 700;
}

/* ---------- 10. 滚动进度条 ---------- */
.progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 120;
  width: 0;
  height: 2px;
  background: var(--amber);
  transition: width 120ms linear;
}

/* ---------- 11. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: 0;
  background: var(--ink);
  color: rgba(246, 241, 231, 0.78);
  border-top: 3px solid var(--amber);
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 10px;
  background-image: repeating-linear-gradient(
    90deg,
    rgba(246, 241, 231, 0.14) 0 1px,
    transparent 1px 40px
  );
  pointer-events: none;
}

.footer__grid {
  display: grid;
  grid-template-columns: 1.1fr 1.5fr 1.15fr;
  gap: clamp(28px, 4vw, 56px);
  padding-block: clamp(40px, 5vw, 72px) clamp(32px, 4vw, 56px);
}

.footer__brand {
  display: grid;
  align-content: start;
  gap: 0.85rem;
}

.footer__lockup {
  font-size: 20px;
  font-weight: 900;
  letter-spacing: 0.11em;
  color: var(--paper);
}

.footer__tagline {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.16em;
  color: var(--amber-2);
}

.footer__desc {
  max-width: 28ch;
  font-size: 13.5px;
  line-height: 1.8;
  color: rgba(246, 241, 231, 0.66);
}

.footer__quick {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.25rem;
}

.footer__quick a {
  display: inline-block;
  padding: 0.4rem 0.7rem;
  font-size: 12px;
  letter-spacing: 0.1em;
  text-decoration: none;
  color: rgba(246, 241, 231, 0.84);
  border: 1px solid rgba(246, 241, 231, 0.26);
  transition: border-color var(--dur) var(--ease),
              color var(--dur) var(--ease),
              transform var(--dur) var(--ease);
}

.footer__quick a:hover {
  color: var(--amber-2);
  border-color: var(--amber);
  transform: translateY(-2px);
}

.footer__nav {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.5rem;
}

.footer__col ul {
  display: grid;
  gap: 0.55rem;
}

.footer__col a {
  font-size: 13.5px;
  letter-spacing: 0.04em;
  text-decoration: none;
  color: rgba(246, 241, 231, 0.72);
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease),
              border-color var(--dur) var(--ease);
}

.footer__col a:hover {
  color: var(--paper);
  border-bottom-color: var(--amber);
}

.footer__col-title {
  margin-bottom: 0.9rem;
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 0.2em;
  color: var(--amber-2);
}

.footer__contact {
  display: grid;
  align-content: start;
  gap: 0.9rem;
}

.footer__meta {
  display: grid;
  gap: 0.7rem;
  font-size: 13.5px;
}

.footer__meta div {
  display: grid;
  gap: 0.1rem;
}

.footer__meta dt {
  font-size: 10.5px;
  letter-spacing: 0.2em;
  color: rgba(246, 241, 231, 0.44);
}

.footer__meta dd {
  margin: 0;
  color: rgba(246, 241, 231, 0.88);
  word-break: break-word;
}

.footer__meta dd .mono {
  font-size: 13px;
  letter-spacing: 0.02em;
}

.footer__note {
  padding-left: 0.7rem;
  border-left: 2px solid var(--celadon);
  font-size: 12px;
  line-height: 1.75;
  letter-spacing: 0.02em;
  color: rgba(246, 241, 231, 0.56);
}

.footer__bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem 1.5rem;
  padding-block: 1.1rem;
  border-top: 1px solid rgba(246, 241, 231, 0.16);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: rgba(246, 241, 231, 0.55);
}

.footer__copy {
  letter-spacing: 0.08em;
}

.footer__legal {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-inline: auto;
}

.footer__legal a {
  text-decoration: none;
  color: rgba(246, 241, 231, 0.62);
  transition: color var(--dur) var(--ease);
}

.footer__legal a:hover {
  color: var(--amber-2);
}

.footer__icp {
  font-size: 11px;
  letter-spacing: 0.08em;
  color: rgba(246, 241, 231, 0.5);
}

/* ---------- 12. 通用按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.55em;
  padding: 0.85rem 1.4rem;
  border: 1px solid var(--ink);
  border-radius: 0;
  background: var(--ink);
  color: var(--paper);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-align: center;
  text-decoration: none;
  cursor: pointer;
  transition: background-color var(--dur) var(--ease),
              border-color var(--dur) var(--ease),
              color var(--dur) var(--ease),
              transform var(--dur) var(--ease);
}

.btn:hover {
  transform: translateY(-2px);
  background: var(--ink-soft);
  border-color: var(--ink-soft);
}

.btn--amber {
  background: var(--amber);
  border-color: var(--amber);
  color: #23180A;
}

.btn--amber:hover {
  background: #C67C21;
  border-color: #C67C21;
  color: #23180A;
}

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

.btn--ghost:hover {
  background: var(--paper-2);
  border-color: var(--ink);
  color: var(--ink);
}

.btn--arrow::after {
  content: "→";
  font-family: var(--font-mono);
  font-size: 0.92em;
}

/* ---------- 13. 标签与筛选 ---------- */
.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.45rem 0.9rem;
  border: 1px solid rgba(14, 42, 63, 0.22);
  border-radius: 0;
  background: var(--white);
  color: var(--ink);
  font-size: 13px;
  letter-spacing: 0.06em;
  cursor: pointer;
  transition: border-color var(--dur) var(--ease),
              transform var(--dur) var(--ease),
              background-color var(--dur) var(--ease),
              color var(--dur) var(--ease);
}

.chip:hover {
  transform: translateY(-2px);
  border-color: var(--amber);
}

.chip[aria-pressed="true"],
.chip.is-active {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--paper);
}

.chip[aria-pressed="true"]::before,
.chip.is-active::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--celadon);
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.4em;
  padding: 0.22rem 0.6rem;
  background: var(--amber-2);
  color: #3A250A;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.12em;
}

.tag--ink {
  background: var(--ink-soft);
  color: var(--paper);
}

.tag--celadon {
  background: rgba(62, 124, 106, 0.14);
  color: #2C5A4D;
  box-shadow: inset 0 0 0 1px rgba(62, 124, 106, 0.4);
}

/* ---------- 14. 章节标题与注释 ---------- */
.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.5rem 1rem;
  margin-bottom: 1.5rem;
  padding-bottom: 0.9rem;
  border-bottom: 1px solid var(--line);
}

.section-head__index {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--amber);
}

.section-title {
  position: relative;
  padding-left: 0.85rem;
  font-size: clamp(22px, 2.6vw, 30px);
  font-weight: 900;
  line-height: 1.2;
  letter-spacing: 0.05em;
}

.section-title::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.15em;
  bottom: 0.15em;
  width: 2px;
  background: var(--amber);
}

.kicker {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.2em;
  color: var(--mist);
}

.note {
  font-size: 13px;
  line-height: 1.7;
  letter-spacing: 0.1em;
  color: var(--mist);
}

.annot {
  writing-mode: vertical-rl;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.3em;
  color: rgba(14, 42, 63, 0.55);
  user-select: none;
}

/* ---------- 15. 卡片与 Bento ---------- */
.card {
  display: flex;
  flex-direction: column;
  min-width: 0;
  background: var(--white);
  border: 1px solid var(--line);
}

.card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.7rem 1rem;
  border-bottom: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--mist);
}

.card__body {
  display: grid;
  align-content: start;
  gap: 0.6rem;
  padding: 1.1rem;
}

.card--paper {
  background: var(--paper-2);
}

.card--ink {
  background: var(--ink);
  border-color: var(--ink);
  color: rgba(246, 241, 231, 0.82);
}

.card--ink .card__head {
  border-bottom-color: var(--line-light);
  color: rgba(246, 241, 231, 0.58);
}

.card--ink h3,
.card--ink h2 {
  color: var(--paper);
}

/* ---------- 16. 时间轴 / 指标 ---------- */
.timeline {
  display: grid;
  border-top: 1px solid var(--line);
}

.timeline__item {
  position: relative;
  display: grid;
  gap: 0.25rem;
  padding: 0.95rem 0 0.95rem 1.4rem;
  border-bottom: 1px solid var(--line);
}

.timeline__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 1.4rem;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--amber);
  box-shadow: 0 0 0 3px rgba(217, 138, 43, 0.16);
}

.stat {
  display: grid;
  gap: 0.15rem;
}

.stat__num {
  font-family: var(--font-mono);
  font-size: clamp(26px, 3.4vw, 38px);
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--ink);
}

.stat__label {
  font-size: 11.5px;
  letter-spacing: 0.16em;
  color: var(--mist);
}

/* ---------- 17. 图片容器基础规则 ---------- */
.figure {
  display: grid;
  gap: 0.6rem;
  margin: 0;
}

.figure__frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 4 / 3;
  border: 1px solid var(--line);
  background: var(--paper-2);
}

.figure__frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.85) contrast(1.03);
}

.figure__frame::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--amber);
  opacity: 0.08;
  mix-blend-mode: multiply;
  pointer-events: none;
}

.figure__caption {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.14em;
  color: var(--mist);
}

.figure--wide .figure__frame { aspect-ratio: 16 / 9; }
.figure--tall .figure__frame { aspect-ratio: 3 / 4; }
.figure--square .figure__frame { aspect-ratio: 1 / 1; }

.figure__frame--empty {
  display: grid;
  place-items: center;
  background-image: repeating-linear-gradient(
    135deg,
    rgba(14, 42, 63, 0.07) 0 1px,
    transparent 1px 12px
  );
}

.figure__frame--empty::before {
  content: "航运影像位";
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.3em;
  color: rgba(14, 42, 63, 0.38);
}

/* ---------- 18. 手风琴 ---------- */
.accordion {
  border-top: 1px solid var(--line);
}

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

.accordion__trigger {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  width: 100%;
  padding: 1rem 0 1rem 1.05rem;
  text-align: left;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--ink);
  cursor: pointer;
  transition: color var(--dur) var(--ease);
}

.accordion__trigger::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.9rem;
  bottom: 0.9rem;
  width: 2px;
  background: var(--amber);
  opacity: 0;
  transition: opacity var(--dur) var(--ease);
}

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

.accordion__trigger[aria-expanded="true"]::before { opacity: 1; }

.accordion__icon {
  flex: none;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--amber);
  transition: transform var(--dur) var(--ease);
}

.accordion__trigger[aria-expanded="true"] .accordion__icon {
  transform: rotate(90deg);
}

.accordion__panel {
  max-width: 42em;
  padding: 0 0 1.15rem 1.05rem;
  font-size: 15px;
  line-height: 1.85;
  color: var(--graphite);
}

/* ---------- 19. 锚点轨 / 复制按钮 / 面包屑 ---------- */
.anchor-rail {
  display: grid;
  gap: 0.75rem;
  font-size: 12px;
  letter-spacing: 0.1em;
}

.anchor-rail a {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  text-decoration: none;
  color: var(--mist);
  transition: color var(--dur) var(--ease);
}

.anchor-rail a::before {
  content: "";
  width: 14px;
  height: 1px;
  background: var(--line-strong);
  transition: width var(--dur) var(--ease),
              background-color var(--dur) var(--ease);
}

.anchor-rail a:hover { color: var(--ink); }

.anchor-rail a[aria-current="true"] {
  color: var(--ink);
  font-weight: 700;
}

.anchor-rail a[aria-current="true"]::before {
  width: 22px;
  background: var(--amber);
}

.copy {
  padding: 0.25rem 0.5rem;
  border: 1px solid var(--line);
  background: var(--white);
  color: var(--ink-soft);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  cursor: pointer;
  transition: border-color var(--dur) var(--ease),
              color var(--dur) var(--ease);
}

.copy:hover {
  border-color: var(--amber);
  color: var(--ink);
}

.breadcrumbs {
  font-size: 11.5px;
  letter-spacing: 0.12em;
  color: var(--mist);
}

.breadcrumbs ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
}

.breadcrumbs a {
  color: var(--ink-soft);
  text-decoration: none;
}

.breadcrumbs a:hover {
  color: var(--ink);
  text-decoration: underline;
  text-decoration-color: var(--amber);
}

.breadcrumbs li + li::before {
  content: "/";
  margin-right: 0.5rem;
  color: var(--line-strong);
}

/* ---------- 20. 正文容器 ---------- */
.prose {
  max-width: 40em;
  font-size: 17px;
  line-height: 1.85;
  letter-spacing: 0.01em;
  color: var(--graphite);
}

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

.prose h2 {
  margin-top: 2em;
  font-size: clamp(20px, 2.2vw, 26px);
  letter-spacing: 0.05em;
}

.prose h3 {
  margin-top: 1.6em;
  font-size: 17px;
  letter-spacing: 0.06em;
  color: var(--ink-soft);
}

.prose ul,
.prose ol { padding-left: 1.3em; }

.prose ul { list-style: square; }
.prose ol { list-style: decimal; }

.prose li + li { margin-top: 0.4em; }

.prose a {
  color: var(--ink-soft);
  text-decoration: underline;
  text-decoration-color: var(--amber);
}

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

.prose blockquote {
  padding-left: 1rem;
  border-left: 2px solid var(--amber);
  color: var(--ink-soft);
}

.prose code {
  padding: 0.1em 0.35em;
  background: var(--paper-2);
  font-family: var(--font-mono);
  font-size: 0.9em;
}

.prose table {
  border-top: 1px solid var(--line);
  font-size: 14px;
}

.prose th,
.prose td {
  padding: 0.6rem 0.7rem;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

.prose th {
  background: var(--paper-2);
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--ink);
}

/* ---------- 21. 响应式 ---------- */
@media (max-width: 1100px) {
  .site-nav {
    display: none;
    order: 4;
    flex: 1 0 100%;
    margin-inline: 0;
    background: var(--ink-soft);
    border-top: 1px solid var(--line-light);
  }

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

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding-block: 0.35rem;
  }

  .site-nav__link {
    padding: 0.8rem 0.9rem;
    border-bottom: 1px solid rgba(246, 241, 231, 0.1);
    border-left: 2px solid transparent;
  }

  .site-nav__link[aria-current="page"] {
    border-bottom-color: rgba(246, 241, 231, 0.1);
    border-left-color: var(--amber);
    background: rgba(246, 241, 231, 0.07);
  }

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

  .command {
    margin-left: auto;
  }
}

@media (max-width: 960px) {
  .footer__grid {
    grid-template-columns: 1fr 1fr;
  }

  .footer__contact {
    grid-column: 1 / -1;
  }

  .grid {
    grid-template-columns: repeat(6, minmax(0, 1fr));
  }

  .bento {
    grid-template-columns: repeat(6, minmax(0, 1fr));
  }
}

@media (max-width: 720px) {
  body { font-size: 15.5px; }

  .utility-bar__list { display: none; }

  .command-bar__inner {
    gap: 10px;
    padding-block: 10px;
  }

  .brand__mark {
    width: 34px;
    height: 34px;
    font-size: 11.5px;
  }

  .brand__tagline { display: none; }

  .brand__name { font-size: 15px; }

  .nav-toggle {
    order: 2;
    margin-left: auto;
  }

  .command {
    order: 3;
    flex: 1 0 100%;
    max-width: none;
    margin-left: 0;
  }

  .command__results {
    position: static;
    margin-top: 0.5rem;
    box-shadow: none;
  }

  .footer__grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .footer__nav {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1.75rem;
  }

  .footer__legal {
    margin-inline: 0;
  }

  .footer__desc { max-width: none; }
}

@media (max-width: 560px) {
  .grid,
  .bento {
    grid-template-columns: 1fr;
  }

  .btn {
    width: 100%;
  }

  .footer__bottom {
    font-size: 11px;
    letter-spacing: 0.06em;
  }
}

/* ---------- 22. 可访问性偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .btn:hover,
  .chip:hover,
  .footer__quick a:hover {
    transform: none;
  }

  .progress { transition: none; }
}