/* =========================================================
   /assets/site.css — 启博EPN 共享外壳样式
   高原观测站：晨雾白底 / 湖心蓝线 / 经幡橙锚点 / 精密刻度
   ========================================================= */

/* ---------- 1. Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 92px;
  font-size: 16px;
}
body, h1, h2, h3, h4, h5, h6, p, ul, ol, li, figure, figcaption, blockquote, dl, dt, dd {
  margin: 0; padding: 0;
}
ul, ol { list-style: none; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
img, svg, video { display: block; max-width: 100%; }
table { border-collapse: collapse; width: 100%; }
input, textarea, select { font: inherit; }

/* ---------- 2. Tokens ---------- */
:root {
  --lake-deep: #0E4C6B;
  --lake: #2C7FA6;
  --mist: #F6F8F7;
  --paper: #F1E9DC;
  --orange: #D96A2B;
  --orange-deep: #C05A1F;
  --jade: #2A8578;
  --ink: #17262E;
  --line: #C6D0D6;
  --red: #A6392F;
  --glow: #BFE0EA;

  --ink-soft: rgba(23, 38, 46, 0.72);
  --ink-faint: rgba(23, 38, 46, 0.52);
  --sea-soft: rgba(14, 76, 107, 0.62);
  --on-deep: rgba(246, 248, 247, 0.82);
  --on-deep-faint: rgba(246, 248, 247, 0.56);
  --hair: rgba(198, 208, 214, 0.7);
  --hair-deep: rgba(198, 208, 214, 0.18);

  --f-display: 'Noto Sans SC', 'Source Han Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --f-body: 'Noto Sans SC', 'Source Han Sans SC', 'PingFang SC', sans-serif;
  --f-serif: 'Noto Serif SC', 'Songti SC', serif;
  --f-mono: 'IBM Plex Mono', ui-monospace, 'SFMono-Regular', Menlo, monospace;

  --wrap: 1240px;
  --wrap-wide: 1440px;
  --wrap-narrow: 760px;
  --gut: 20px;
  --r-sm: 4px;

  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --t-fast: 160ms;
  --t-mid: 240ms;
  --t-slow: 420ms;
}

@media (min-width: 768px) { :root { --gut: 28px; } }
@media (min-width: 1024px) { :root { --gut: 40px; font-size: 17px; } }

/* ---------- 3. Base typography ---------- */
body {
  font-family: var(--f-body);
  font-size: 1rem;
  line-height: 1.85;
  font-weight: 400;
  color: var(--ink);
  background-color: var(--mist);
  background-image:
    linear-gradient(to right, rgba(198, 208, 214, 0.22) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(198, 208, 214, 0.22) 1px, transparent 1px);
  background-size: 160px 160px;
  background-position: -1px -1px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5 {
  font-family: var(--f-display);
  line-height: 1.28;
  letter-spacing: -0.01em;
  color: var(--ink);
}
h1 { font-size: clamp(28px, 4.2vw, 52px); font-weight: 800; }
h2 { font-size: clamp(20px, 2.4vw, 30px); font-weight: 700; }
h3 { font-size: clamp(17px, 1.5vw, 20px); font-weight: 700; }
h4 { font-size: 16px; font-weight: 700; }
p { max-width: 76ch; }
strong, b { font-weight: 700; }
code, kbd, samp { font-family: var(--f-mono); font-size: 0.86em; letter-spacing: 0.04em; }
::selection { background: var(--glow); color: var(--lake-deep); }

:focus-visible {
  outline: 2px solid var(--orange);
  outline-offset: 2px;
  border-radius: 2px;
}
.site-header :focus-visible,
.section--deep :focus-visible,
.site-footer :focus-visible {
  outline-color: var(--glow);
}

/* ---------- 4. Layout primitives ---------- */
.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--gut);
}
.wrap--wide { max-width: var(--wrap-wide); }
.wrap--narrow { max-width: var(--wrap-narrow); }

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: 24px;
}
.col-4  { grid-column: span 4; }
.col-5  { grid-column: span 5; }
.col-6  { grid-column: span 6; }
.col-7  { grid-column: span 7; }
.col-8  { grid-column: span 8; }
.col-12 { grid-column: 1 / -1; }
.col-off-1 { grid-column-start: 2; }

@media (max-width: 860px) {
  .grid-12 { grid-template-columns: minmax(0, 1fr); gap: 20px; }
  .col-4, .col-5, .col-6, .col-7, .col-8, .col-12 { grid-column: 1 / -1; }
  .col-off-1 { grid-column-start: auto; }
}

.stack > * + * { margin-top: var(--stack-gap, 24px); }
.stack--tight { --stack-gap: 12px; }
.stack--loose { --stack-gap: 48px; }

.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;
}

#main-content { display: block; }

/* ---------- 5. Sections & editorial rhythm ---------- */
.section { padding-block: clamp(56px, 8vw, 96px); }
.section--paper { background: var(--paper); }
.section--deep { background: var(--lake-deep); color: var(--mist); }
.section--deep h1, .section--deep h2, .section--deep h3, .section--deep h4 { color: var(--mist); }
.section--deep .lede { color: rgba(246, 248, 247, 0.76); }
.section--line { border-top: 1px solid var(--line); }

.page-head { padding-block: clamp(30px, 5vw, 64px) clamp(8px, 2vw, 18px); }

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 14px 32px;
  margin-bottom: clamp(28px, 4vw, 48px);
}
.section-head__text { max-width: 62ch; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--f-serif);
  font-size: 15px;
  letter-spacing: 0.04em;
  color: var(--lake);
}
.eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  background: currentColor;
  opacity: 0.65;
}
.section--deep .eyebrow { color: var(--glow); }

.lede {
  font-size: clamp(16px, 1.35vw, 18px);
  line-height: 1.9;
  color: var(--ink-soft);
  max-width: 62ch;
}

.note {
  background: var(--paper);
  border-left: 2px solid var(--orange);
  padding: 14px 18px;
  font-size: 13px;
  line-height: 1.75;
  color: var(--ink-soft);
  max-width: 68ch;
}
.note p { max-width: none; }

/* ---------- 6. Buttons & links ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--f-display);
  font-weight: 700;
  font-size: 14px;
  letter-spacing: 0.02em;
  line-height: 1;
  padding: 12px 20px;
  border: 1px solid transparent;
  border-radius: var(--r-sm);
  white-space: nowrap;
  transition:
    background-color var(--t-fast) var(--ease),
    border-color var(--t-fast) var(--ease),
    color var(--t-fast) var(--ease),
    transform var(--t-fast) var(--ease);
}
.btn:active { transform: translateY(1px); }

.btn--signal { background: var(--orange); border-color: var(--orange); color: #fff; }
.btn--signal:hover { background: var(--orange-deep); border-color: var(--orange-deep); }

.btn--ghost { background: transparent; border-color: var(--line); color: var(--lake-deep); }
.btn--ghost:hover { background: var(--glow); border-color: var(--lake); }

.btn--deep { background: var(--lake-deep); border-color: var(--lake-deep); color: var(--mist); }
.btn--deep:hover { background: var(--lake); border-color: var(--lake); }

.link-arrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-weight: 600;
  color: var(--lake);
  transition: color var(--t-fast) var(--ease);
}
.link-arrow::after {
  content: "→";
  transition: transform var(--t-fast) var(--ease);
}
.link-arrow:hover { color: var(--lake-deep); }
.link-arrow:hover::after { transform: translateX(4px); }

/* ---------- 7. Skip link ---------- */
.skip-link {
  position: absolute;
  left: 14px;
  top: -70px;
  z-index: 200;
  padding: 10px 16px;
  background: var(--ink);
  color: var(--mist);
  font-size: 13px;
  border-radius: var(--r-sm);
  transition: top var(--t-fast) var(--ease);
}
.skip-link:focus { top: 14px; }

/* ---------- 8. Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  background: var(--lake-deep);
  color: var(--mist);
  border-bottom: 1px solid rgba(246, 248, 247, 0.14);
}
.site-header::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(90deg, rgba(191, 224, 234, 0.12), rgba(191, 224, 234, 0) 46%);
}
.header-inner {
  position: relative;
  width: 100%;
  max-width: var(--wrap-wide);
  margin-inline: auto;
  padding-inline: var(--gut);
  min-height: 70px;
  display: flex;
  align-items: center;
  gap: 24px;
}
.header-scale {
  position: absolute;
  left: 0; right: 0; bottom: 0;
  height: 5px;
  pointer-events: none;
  opacity: 0.5;
  background-image: repeating-linear-gradient(
    90deg,
    rgba(191, 224, 234, 0.5) 0 1px,
    transparent 1px 12px
  );
}

/* brand */
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 0 0 auto;
  padding-block: 10px;
}
.brand__mark {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  line-height: 1;
  padding: 7px 7px 6px;
  color: var(--glow);
  border: 1px solid rgba(191, 224, 234, 0.5);
  border-radius: 2px;
  transition: color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}
.brand:hover .brand__mark { color: #fff; border-color: #fff; }
.brand__text { display: flex; flex-direction: column; gap: 1px; min-width: 0; }
.brand__name {
  font-family: var(--f-display);
  font-weight: 800;
  font-size: 17px;
  letter-spacing: 0.01em;
  line-height: 1.25;
  color: #fff;
}
.brand__line {
  font-family: var(--f-serif);
  font-size: 12px;
  line-height: 1.4;
  color: var(--on-deep-faint);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* toggle */
.nav-toggle {
  display: none;
  margin-inline-start: auto;
  align-items: center;
  gap: 9px;
  padding: 9px 12px;
  border: 1px solid rgba(191, 224, 234, 0.42);
  border-radius: var(--r-sm);
  color: var(--mist);
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  transition: background-color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}
.nav-toggle:hover { background: rgba(191, 224, 234, 0.12); border-color: var(--glow); }
.nav-toggle__bars { display: flex; flex-direction: column; gap: 3px; width: 14px; }
.nav-toggle__bars i {
  display: block;
  height: 1px;
  background: currentColor;
  transition: transform var(--t-fast) var(--ease), opacity var(--t-fast) var(--ease);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(1) { transform: translateY(4px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(3) { transform: translateY(-4px) rotate(-45deg); }
.nav-toggle__label { line-height: 1; }

/* navigation */
.site-nav {
  margin-inline-start: auto;
  display: flex;
  align-items: center;
  gap: 20px;
}
.nav-index { display: flex; align-items: center; gap: 2px; }
.nav-index__item { display: flex; }
.nav-index a {
  display: flex;
  align-items: baseline;
  gap: 6px;
  padding: 10px 11px 9px;
  font-size: 14px;
  font-weight: 500;
  color: var(--on-deep);
  border-bottom: 2px solid transparent;
  transition:
    color var(--t-fast) var(--ease),
    background-color var(--t-fast) var(--ease),
    border-color var(--t-fast) var(--ease);
}
.nav-index a:hover { color: #fff; background: rgba(246, 248, 247, 0.08); }
.nav-index a[aria-current="page"] {
  color: #fff;
  background: rgba(191, 224, 234, 0.14);
  border-bottom-color: var(--orange);
}
.nav-index__num {
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: 0.08em;
  color: rgba(191, 224, 234, 0.62);
  transition: color var(--t-fast) var(--ease);
}
.nav-index a[aria-current="page"] .nav-index__num { color: var(--orange); }
.nav-index__label { line-height: 1.2; }

.nav-tail { display: flex; align-items: center; gap: 12px; }
.nav-tail__cta { white-space: nowrap; }

/* ---------- 9. Footer ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(64px, 9vw, 120px);
  padding-block: clamp(52px, 6vw, 84px) 0;
  background: var(--ink);
  color: var(--on-deep);
  overflow: hidden;
}
.footer-scale {
  position: absolute;
  left: 0; right: 0; top: 0;
  height: 6px;
  pointer-events: none;
  opacity: 0.5;
  background-image: repeating-linear-gradient(
    90deg,
    rgba(191, 224, 234, 0.3) 0 1px,
    transparent 1px 16px
  );
}
.footer-top {
  display: grid;
  grid-template-columns: minmax(0, 4fr) minmax(0, 7fr);
  gap: clamp(32px, 5vw, 72px);
  padding-block-end: clamp(30px, 4vw, 46px);
  border-bottom: 1px solid var(--hair-deep);
}
.footer-brand__name {
  font-family: var(--f-display);
  font-weight: 800;
  font-size: clamp(18px, 1.8vw, 22px);
  line-height: 1.45;
  color: var(--mist);
}
.footer-brand__region {
  margin-top: 10px;
  font-family: var(--f-serif);
  font-size: 14px;
  line-height: 1.7;
  color: var(--on-deep-faint);
  max-width: 30ch;
}
.footer-brand__icp {
  margin-top: 16px;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: rgba(191, 224, 234, 0.7);
}
.footer-nav {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 40px);
}
.footer-col__title {
  font-family: var(--f-serif);
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--glow);
  margin-bottom: 14px;
}
.footer-col__list li + li { margin-top: 9px; }
.footer-col__list a {
  font-size: 14px;
  color: var(--on-deep);
  border-bottom: 1px solid transparent;
  transition: color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}
.footer-col__list a:hover { color: #fff; border-bottom-color: var(--orange); }

.footer-contact {
  padding-block: clamp(26px, 3.4vw, 40px);
  border-bottom: 1px solid var(--hair-deep);
}
.contact-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px 32px;
}
.contact-grid__item dt {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: rgba(191, 224, 234, 0.66);
  margin-bottom: 6px;
}
.contact-grid__item dd {
  font-size: 14px;
  line-height: 1.7;
  color: var(--on-deep);
  overflow-wrap: anywhere;
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 24px;
  padding-block: 22px 30px;
  font-size: 12px;
  color: var(--on-deep-faint);
}
.footer-bottom__copy { font-family: var(--f-mono); letter-spacing: 0.06em; max-width: none; }
.footer-bottom__links { display: flex; flex-wrap: wrap; gap: 8px 18px; }
.footer-bottom__links a { color: rgba(191, 224, 234, 0.82); transition: color var(--t-fast) var(--ease); }
.footer-bottom__links a:hover { color: #fff; }
.footer-bottom__note {
  margin-inline-start: auto;
  font-family: var(--f-serif);
  max-width: none;
}

/* ---------- 10. Scroll progress & back-to-top ---------- */
.scroll-progress {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 2px;
  z-index: 120;
  pointer-events: none;
  background: transparent;
}
.scroll-progress__fill {
  display: block;
  height: 100%;
  width: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--lake), var(--glow) 55%, var(--orange));
}

.to-top {
  position: fixed;
  right: clamp(14px, 3vw, 32px);
  bottom: clamp(14px, 3vw, 32px);
  z-index: 100;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 7px;
  padding: 12px 14px;
  background: var(--mist);
  border: 1px solid var(--line);
  border-radius: 2px;
  color: var(--lake-deep);
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  box-shadow: 0 10px 26px rgba(23, 38, 46, 0.1);
  transition:
    opacity var(--t-mid) var(--ease),
    transform var(--t-mid) var(--ease),
    border-color var(--t-fast) var(--ease),
    visibility 0s linear var(--t-mid);
}
.to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: none;
  transition:
    opacity var(--t-mid) var(--ease),
    transform var(--t-mid) var(--ease),
    border-color var(--t-fast) var(--ease),
    visibility 0s;
}
.to-top:hover { border-color: var(--lake); }
.to-top__label { line-height: 1; }
.to-top__meter {
  display: block;
  width: 46px;
  height: 2px;
  background: var(--line);
  overflow: hidden;
}
.to-top__meter-fill {
  display: block;
  height: 100%;
  width: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: var(--orange);
}
.to-top__num { color: var(--ink-faint); letter-spacing: 0.08em; line-height: 1; }

/* ---------- 11. Table of contents ---------- */
.toc {
  border: 1px solid var(--line);
  background: #FFFFFF;
  padding: 18px 18px 20px;
}
.toc__title {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--f-serif);
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--lake);
  margin-bottom: 12px;
}
.toc__title::after { content: ""; flex: 1; height: 1px; background: var(--line); }
.toc__list { counter-reset: toc; }
.toc__link {
  position: relative;
  display: block;
  padding: 8px 10px 8px 32px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--ink-soft);
  border-left: 2px solid transparent;
  transition:
    background-color var(--t-fast) var(--ease),
    color var(--t-fast) var(--ease),
    border-color var(--t-fast) var(--ease);
}
.toc__link::before {
  counter-increment: toc;
  content: counter(toc, decimal-leading-zero);
  position: absolute;
  left: 10px;
  top: 9px;
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: 0.06em;
  color: var(--ink-faint);
}
.toc__link:hover { background: var(--paper); color: var(--lake-deep); }
.toc__link.is-current {
  background: var(--glow);
  color: var(--lake-deep);
  border-left-color: var(--orange);
  font-weight: 600;
}
.toc__link.is-current::before { color: var(--orange); }

/* ---------- 12. Accordion ---------- */
.accordion { display: grid; gap: 12px; }
.accordion__item {
  border: 1px solid var(--line);
  background: #FFFFFF;
  transition: border-color var(--t-fast) var(--ease);
}
.accordion__item:hover { border-color: var(--lake); }
.accordion__item[data-open] { border-color: var(--lake); }
.accordion__trigger {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 18px;
  text-align: left;
  font-family: var(--f-display);
  font-weight: 700;
  font-size: 16px;
  line-height: 1.6;
  color: var(--ink);
  transition: background-color var(--t-fast) var(--ease);
}
.accordion__trigger:hover { background: var(--paper); }
.accordion__mark {
  position: relative;
  flex: 0 0 auto;
  width: 22px;
  height: 22px;
  border: 1px solid var(--line);
  border-radius: 2px;
  transition: background-color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}
.accordion__mark::before,
.accordion__mark::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  background: var(--lake);
  transform: translate(-50%, -50%);
  transition: opacity var(--t-fast) var(--ease);
}
.accordion__mark::before { width: 10px; height: 1px; }
.accordion__mark::after { width: 1px; height: 10px; }
.accordion__item[data-open] .accordion__mark { background: var(--orange); border-color: var(--orange); }
.accordion__item[data-open] .accordion__mark::before { background: #fff; }
.accordion__item[data-open] .accordion__mark::after { opacity: 0; }
.accordion__panel {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--t-mid) var(--ease);
}
.accordion__panel-inner {
  padding: 2px 18px 20px 54px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-soft);
}
.accordion__panel-inner p { max-width: 62ch; }

/* ---------- 13. Path rail ---------- */
.path-rail {
  position: relative;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 20px;
  padding-top: 30px;
}
.path-rail::before {
  content: "";
  position: absolute;
  top: 8px;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, var(--lake), var(--line) 60%, transparent);
}
.path-node {
  position: relative;
  display: block;
  padding-top: 26px;
}
.path-node__dot {
  position: absolute;
  top: -9px;
  left: 0;
  width: 9px;
  height: 9px;
  background: var(--mist);
  border: 1px solid var(--lake);
  border-radius: 50%;
  transition:
    background-color var(--t-fast) var(--ease),
    border-color var(--t-fast) var(--ease),
    transform var(--t-fast) var(--ease);
}
.path-node:hover .path-node__dot,
.path-node:focus-visible .path-node__dot {
  background: var(--orange);
  border-color: var(--orange);
  transform: scale(1.3);
}
.path-node__label {
  display: block;
  font-family: var(--f-display);
  font-weight: 700;
  font-size: 15px;
  color: var(--lake-deep);
}
.path-node__meta {
  display: block;
  margin-top: 4px;
  font-family: var(--f-serif);
  font-size: 13px;
  line-height: 1.65;
  color: var(--ink-faint);
}

/* ---------- 14. Step cards ---------- */
.step-list { display: grid; }
.step-card {
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr);
  gap: 18px;
  padding: 24px 0;
  border-bottom: 1px solid var(--line);
}
.step-card:first-child { padding-top: 0; }
.step-card__index {
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--lake);
  padding-top: 5px;
}
.step-card__body h3 { margin-bottom: 6px; }
.step-card__body p { font-size: 15px; color: var(--ink-soft); }

/* ---------- 15. Compare block ---------- */
.compare {
  width: 100%;
  border: 1px solid var(--line);
  background: #FFFFFF;
}
.compare__row {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr) minmax(0, 1fr);
}
.compare__row + .compare__row { border-top: 1px solid var(--line); }
.compare__col {
  padding: 14px 16px;
  font-size: 14px;
  line-height: 1.75;
}
.compare__col + .compare__col { border-left: 1px solid var(--line); }
.compare__col p { max-width: none; }

@media (max-width: 720px) {
  .compare__row { grid-template-columns: minmax(0, 1fr); }
  .compare__col + .compare__col { border-left: 0; border-top: 1px dashed var(--line); }
}

/* ---------- 16. Media containers ---------- */
.media {
  position: relative;
  display: block;
  width: 100%;
  border: 1px solid var(--line);
  background: var(--paper);
  overflow: hidden;
}
.media--16x9 { aspect-ratio: 16 / 9; }
.media--4x3  { aspect-ratio: 4 / 3; }
.media--3x2  { aspect-ratio: 3 / 2; }
.media--1x1  { aspect-ratio: 1 / 1; }
.media--plain { border: 0; background: none; }
.media img,
.media picture > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.media.is-empty::after {
  content: "图像位";
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--sea-soft);
  background-image: repeating-linear-gradient(
    135deg,
    rgba(44, 127, 166, 0.07) 0 8px,
    transparent 8px 16px
  );
}
.media__caption {
  margin-top: 8px;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  line-height: 1.7;
  color: var(--ink-faint);
}

/* ---------- 17. Breadcrumb ---------- */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  padding-block: 18px;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--ink-faint);
}
.breadcrumb li { display: flex; align-items: center; }
.breadcrumb li + li::before {
  content: "/";
  margin-inline-end: 8px;
  color: var(--line);
}
.breadcrumb a { transition: color var(--t-fast) var(--ease); }
.breadcrumb a:hover { color: var(--lake); }
.breadcrumb [aria-current="page"] { color: var(--ink-soft); }

/* ---------- 18. Mobile navigation ---------- */
@media (max-width: 1000px) {
  .header-inner { min-height: 62px; }
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    display: block;
    margin: 0;
    background: var(--lake-deep);
    border-top: 1px solid rgba(246, 248, 247, 0.16);
    border-bottom: 1px solid rgba(191, 224, 234, 0.22);
    box-shadow: 0 22px 44px rgba(14, 76, 107, 0.34);
    max-height: 0;
    overflow: hidden;
    visibility: hidden;
    transition: max-height var(--t-mid) var(--ease), visibility 0s linear var(--t-mid);
  }
  .site-nav[data-open] {
    max-height: min(76vh, 660px);
    overflow-y: auto;
    visibility: visible;
    transition: max-height var(--t-mid) var(--ease), visibility 0s;
  }

  .nav-index { display: block; padding: 6px var(--gut) 0; }
  .nav-index__item { display: block; }
  .nav-index a {
    justify-content: flex-start;
    padding: 15px 2px;
    font-size: 16px;
    border-bottom: 1px solid rgba(246, 248, 247, 0.1);
    border-left: 2px solid transparent;
  }
  .nav-index a[aria-current="page"] {
    border-bottom-color: rgba(246, 248, 247, 0.1);
    border-left-color: var(--orange);
    padding-inline-start: 12px;
  }
  .nav-index__num { font-size: 11px; }

  .nav-tail {
    flex-direction: column;
    align-items: stretch;
    padding: 16px var(--gut) 22px;
  }
  .nav-tail__cta { width: 100%; }

  .brand__line { display: none; }
}

/* ---------- 19. Responsive footer ---------- */
@media (max-width: 900px) {
  .footer-top { grid-template-columns: minmax(0, 1fr); }
  .footer-nav { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .contact-grid { grid-template-columns: minmax(0, 1fr); }
  .footer-bottom__note { margin-inline-start: 0; }
}
@media (max-width: 520px) {
  .footer-nav { grid-template-columns: minmax(0, 1fr); }
  .footer-bottom { flex-direction: column; align-items: flex-start; gap: 10px; }
}

/* ---------- 20. Reduced motion ---------- */
@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;
  }
  .scroll-progress__fill,
  .to-top__meter-fill { transition: none; }
}