/* ============================================================
   乐鱼登录 · 共享外壳样式 /assets/site.css
   深夜数据作战室：深海蓝基底 + 唯一高热荧光橙 + 电光青状态点
   ============================================================ */

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

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

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

ul, ol { list-style: none; }

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

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

a { color: inherit; }

table { border-collapse: collapse; }

/* 2. 变量 ------------------------------------------------- */
:root {
  --c-deep: #05192B;
  --c-layer: #0A2740;
  --c-steel: #14395A;
  --c-grayblue: #7E93A3;
  --c-mist: #E6EDF2;
  --c-orange: #FF6A1A;
  --c-amber: #FF9C4A;
  --c-cyan: #2FD1DC;
  --c-ink: #020A12;
  --c-paper: #F2F6F8;

  --line: rgba(126, 147, 163, 0.26);
  --line-strong: rgba(126, 147, 163, 0.48);
  --tint-cyan: rgba(47, 209, 220, 0.09);
  --tint-orange: rgba(255, 106, 26, 0.12);

  --font-sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-cond: "Barlow Condensed", "Oswald", "Arial Narrow", var(--font-sans);
  --font-mono: "IBM Plex Mono", "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --shell: 1240px;
  --gutter: 24px;
  --header-total: 109px;
  --radius: 2px;
  --dur: 180ms;
  --ease: cubic-bezier(0.2, 0.6, 0.2, 1);
}

@media (max-width: 920px) {
  :root {
    --gutter: 18px;
    --header-total: 92px;
  }
}

/* 3. 基础排版 --------------------------------------------- */
body {
  background: var(--c-deep);
  color: var(--c-mist);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.75;
  font-weight: 400;
  letter-spacing: 0.002em;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

h1, h2, h3, h4 { font-weight: 700; letter-spacing: -0.01em; line-height: 1.2; }

strong { font-weight: 700; }

::selection { background: var(--c-orange); color: var(--c-ink); }

:focus-visible {
  outline: 2px solid var(--c-cyan);
  outline-offset: 2px;
  border-radius: 1px;
}

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden; clip: rect(0 0 0 0);
  white-space: nowrap; border: 0;
}

main { padding-top: var(--header-total); display: block; }
main[data-flush] { padding-top: 0; }

/* 4. 容器与栅格 ------------------------------------------- */
.shell {
  width: 100%;
  max-width: var(--shell);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.shell--narrow { max-width: 860px; }

.section { position: relative; padding: 76px 0; }
.section + .section { border-top: 1px solid var(--line); }
.section--tint { background: var(--c-layer); }
.section--deep { background: var(--c-deep); }
.section--paper { background: var(--c-paper); color: var(--c-layer); }
.section--paper .section-title { color: var(--c-layer); }
.section--paper .section-sub { color: #3D5765; }
.section--paper .eyebrow { color: #0B6A73; }

.section-head { display: flex; flex-direction: column; gap: 14px; margin-bottom: 38px; max-width: 62em; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--c-cyan);
}
.eyebrow::before {
  content: "";
  width: 22px;
  height: 1px;
  background: var(--c-orange);
}

.section-title {
  font-size: clamp(26px, 3.6vw, 40px);
  line-height: 1.16;
  color: var(--c-mist);
}

.section-sub {
  max-width: 40em;
  font-size: 16px;
  line-height: 1.78;
  color: var(--c-grayblue);
}

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

.grid { display: grid; gap: 24px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 24px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 20px; }

.grid-split {
  display: grid;
  grid-template-columns: minmax(0, 7fr) minmax(0, 3fr);
  gap: 40px;
  align-items: start;
}

.grid-index {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: 20px;
}
.col-3 { grid-column: span 3; }
.col-4 { grid-column: span 4; }
.col-6 { grid-column: span 6; }
.col-8 { grid-column: span 8; }

.sticky-rail { position: sticky; top: calc(var(--header-total) + 24px); }

@media (max-width: 1080px) {
  .grid-split { grid-template-columns: minmax(0, 1fr); gap: 32px; }
  .sticky-rail { position: static; }
}
@media (max-width: 900px) {
  .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .col-3, .col-4 { grid-column: span 6; }
}
@media (max-width: 640px) {
  .section { padding: 54px 0; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: minmax(0, 1fr); }
  .col-3, .col-4, .col-6, .col-8 { grid-column: span 12; }
}

/* 5. 按钮 ------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 18px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-size: 15px;
  font-weight: 700;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background var(--dur) var(--ease), color var(--dur) var(--ease),
              border-color var(--dur) var(--ease), transform var(--dur) var(--ease);
}
.btn:active { transform: translateY(1px); }

.btn-primary { background: var(--c-orange); color: #04121E; }
.btn-primary:hover { background: var(--c-amber); }

.btn-ghost {
  background: transparent;
  border-color: var(--line-strong);
  color: var(--c-mist);
}
.btn-ghost:hover { border-color: var(--c-cyan); color: var(--c-cyan); }

.btn-quiet {
  background: transparent;
  color: var(--c-grayblue);
  border-color: transparent;
  padding-left: 0;
  padding-right: 0;
}
.btn-quiet:hover { color: var(--c-orange); }

/* 6. 页头 ------------------------------------------------- */
.skip-link {
  position: absolute;
  left: 16px;
  top: -70px;
  z-index: 200;
  padding: 10px 16px;
  background: var(--c-orange);
  color: #04121E;
  font-weight: 700;
  font-size: 14px;
  text-decoration: none;
  transition: top var(--dur) var(--ease);
}
.skip-link:focus { top: 12px; }

.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 80;
  color: var(--c-mist);
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease),
              box-shadow var(--dur) var(--ease);
}
.site-header[data-scrolled] {
  background: rgba(10, 39, 64, 0.95);
  -webkit-backdrop-filter: blur(10px) saturate(1.15);
  backdrop-filter: blur(10px) saturate(1.15);
  border-bottom-color: var(--line);
  box-shadow: 0 10px 28px rgba(2, 10, 18, 0.5);
}

.header-shell { position: relative; }

.header-strip {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  height: 40px;
  border-bottom: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--c-grayblue);
  transition: height var(--dur) var(--ease), opacity var(--dur) var(--ease),
              visibility var(--dur) var(--ease);
}
.site-header[data-scrolled] .header-strip {
  height: 0;
  opacity: 0;
  visibility: hidden;
  overflow: hidden;
  border-bottom-color: transparent;
}

.season-state {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--c-mist);
  white-space: nowrap;
}

.pulse-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--c-cyan);
  animation: pulse-ring 2.2s infinite;
}

@keyframes pulse-ring {
  0% { box-shadow: 0 0 0 0 rgba(47, 209, 220, 0.55); }
  70% { box-shadow: 0 0 0 7px rgba(47, 209, 220, 0); }
  100% { box-shadow: 0 0 0 0 rgba(47, 209, 220, 0); }
}

.utility-list {
  display: flex;
  align-items: center;
  gap: 18px;
  overflow-x: auto;
  scrollbar-width: none;
}
.utility-list::-webkit-scrollbar { display: none; }

.utility-item {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  white-space: nowrap;
}

.utility-key {
  color: var(--c-cyan);
  letter-spacing: 0.14em;
}

.utility-link {
  color: var(--c-grayblue);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.utility-link:hover { color: var(--c-mist); border-bottom-color: var(--c-orange); }

.header-main {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  height: 68px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--c-mist);
  flex: 0 0 auto;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: var(--radius);
  background: linear-gradient(135deg, var(--c-orange), var(--c-amber));
  color: #04121E;
  font-family: var(--font-cond);
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.02em;
  flex: 0 0 auto;
}

.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-name { font-size: 16px; font-weight: 700; }
.brand-line {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.07em;
  color: var(--c-grayblue);
}

.primary-nav { display: flex; align-items: center; }

.nav-list { display: flex; align-items: center; gap: 2px; }
.nav-item { display: flex; }

.nav-link {
  position: relative;
  display: block;
  padding: 10px 12px;
  font-size: 15px;
  font-weight: 500;
  color: var(--c-mist);
  text-decoration: none;
  border-radius: var(--radius);
  transition: color var(--dur) var(--ease), background var(--dur) var(--ease);
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  bottom: 4px;
  height: 1px;
  background: var(--c-orange);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur) var(--ease);
}
.nav-link:hover { color: #FFFFFF; }
.nav-link:hover::after { transform: scaleX(1); }

.nav-link[aria-current="page"] {
  color: var(--c-orange);
}
.nav-link[aria-current="page"]::after { transform: scaleX(1); background: var(--c-cyan); }

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 0 0 auto;
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 8px 12px;
  background: transparent;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  color: var(--c-mist);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}
.nav-toggle:hover { border-color: var(--c-cyan); color: var(--c-cyan); }
.nav-toggle[aria-expanded="true"] { border-color: var(--c-orange); color: var(--c-orange); }

.nav-toggle-bars { position: relative; display: block; width: 16px; height: 10px; }
.nav-toggle-bars::before,
.nav-toggle-bars::after {
  content: "";
  position: absolute;
  left: 0; right: 0;
  height: 1.5px;
  background: currentColor;
  transition: transform var(--dur) var(--ease);
}
.nav-toggle-bars::before { top: 0; }
.nav-toggle-bars::after { bottom: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::before { transform: translateY(4px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::after { transform: translateY(-4px) rotate(-45deg); }

.nav-toggle-label { letter-spacing: 0.04em; }

.scroll-progress {
  position: absolute;
  left: 0; right: 0; bottom: -1px;
  height: 2px;
  background: linear-gradient(90deg, var(--c-orange), var(--c-amber) 42%, var(--c-cyan));
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 90ms linear;
  pointer-events: none;
}

@media (max-width: 920px) {
  .season-state { font-size: 10.5px; }
  .header-strip { height: auto; padding: 8px 0; gap: 12px; }
  .header-main { height: 58px; gap: 12px; }
  .brand-line { display: none; }
  .nav-toggle { display: inline-flex; }

  .primary-nav {
    position: absolute;
    top: 100%;
    left: calc(-1 * var(--gutter));
    right: calc(-1 * var(--gutter));
    display: none;
    flex-direction: column;
    align-items: stretch;
    background: var(--c-ink);
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
    padding: 6px var(--gutter) 20px;
    max-height: calc(100vh - var(--header-total));
    overflow-y: auto;
  }
  .primary-nav[data-open] { display: flex; }

  .nav-list { flex-direction: column; align-items: stretch; gap: 0; }
  .nav-item { display: block; }
  .nav-link {
    padding: 15px 2px;
    font-size: 17px;
    border-bottom: 1px solid var(--line);
    border-radius: 0;
  }
  .nav-link::after { display: none; }
  .nav-link[aria-current="page"] {
    background: var(--tint-orange);
    padding-left: 12px;
  }
}

@media (max-width: 620px) {
  .header-actions .btn-primary { display: none; }
  .utility-item:nth-child(2) { display: none; }
}

/* 7. 页脚 ------------------------------------------------- */
.site-footer {
  background: var(--c-ink);
  color: var(--c-grayblue);
  border-top: 1px solid var(--line);
}

.footer-shell { position: relative; }

.footer-inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.9fr);
  gap: 56px;
  padding: 64px 0 44px;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 14px;
}

.footer-brand-link {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--c-mist);
}

.footer-brand-name { font-size: 18px; font-weight: 700; }

.footer-brand-line {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--c-cyan);
}

.footer-note {
  max-width: 30ch;
  font-size: 14px;
  line-height: 1.75;
  color: var(--c-grayblue);
}

.footer-columns {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 28px;
}

.footer-col {
  border-top: 1px solid var(--line);
  padding-top: 14px;
  min-width: 0;
}

.footer-col-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  font-size: 14px;
  font-weight: 700;
  color: var(--c-mist);
  letter-spacing: 0.02em;
  list-style: none;
  cursor: default;
}
.footer-col-title::-webkit-details-marker { display: none; }

.footer-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 14px;
}

.footer-link {
  font-size: 14px;
  line-height: 1.5;
  color: var(--c-grayblue);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.footer-link:hover,
.footer-link:focus-visible { color: var(--c-mist); border-bottom-color: var(--c-orange); }

.footer-contact {
  font-family: var(--font-mono);
  font-size: 12.5px;
  gap: 14px;
}

.contact-row { display: flex; flex-direction: column; gap: 4px; min-width: 0; }

.contact-label {
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--c-cyan);
}

.contact-value { color: var(--c-mist); line-height: 1.6; word-break: break-word; }

.copy-btn {
  align-self: flex-start;
  margin-top: 4px;
  padding: 4px 9px;
  background: transparent;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  color: var(--c-grayblue);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  cursor: pointer;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease),
              background var(--dur) var(--ease);
}
.copy-btn:hover { border-color: var(--c-cyan); color: var(--c-cyan); }
.copy-btn[data-copied] {
  border-color: var(--c-cyan);
  color: var(--c-cyan);
  background: var(--tint-cyan);
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  border-top: 1px solid var(--line);
  padding: 20px 0 34px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.04em;
}
.footer-legal-text { color: var(--c-grayblue); }
.footer-legal-meta { color: var(--c-grayblue); max-width: 52ch; }

@media (max-width: 980px) {
  .footer-inner { grid-template-columns: minmax(0, 1fr); gap: 38px; padding: 48px 0 32px; }
  .footer-columns { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 720px) {
  .footer-columns { grid-template-columns: minmax(0, 1fr); gap: 0; }
  .footer-col {
    border-top: none;
    border-bottom: 1px solid var(--line);
    padding-top: 0;
  }
  .footer-col-title { padding: 15px 0; cursor: pointer; }
  .footer-col-title::after {
    content: "＋";
    font-family: var(--font-mono);
    font-size: 13px;
    color: var(--c-cyan);
  }
  .footer-col[open] .footer-col-title::after { content: "－"; color: var(--c-orange); }
  .footer-list { margin-top: 0; padding-bottom: 18px; }
  .footer-legal { flex-direction: column; align-items: flex-start; }
}

/* 8. 目录地图 --------------------------------------------- */
.index-list { border-top: 1px solid var(--line); }

.index-item {
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr) auto;
  align-items: baseline;
  gap: 18px;
  padding: 18px 4px;
  border-bottom: 1px solid var(--line);
  transition: background var(--dur) var(--ease);
}
.index-item:hover { background: var(--tint-cyan); }

.index-no {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--c-grayblue);
}

.index-title {
  font-size: 19px;
  font-weight: 700;
  color: var(--c-mist);
}

.index-span {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  color: var(--c-cyan);
  white-space: nowrap;
}

.index-path {
  display: block;
  margin-top: 4px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--c-grayblue);
  text-decoration: none;
}
.index-path:hover { color: var(--c-orange); }

@media (max-width: 640px) {
  .index-item { grid-template-columns: 44px minmax(0, 1fr); gap: 12px; }
  .index-span { grid-column: 2; }
}

/* 9. 数据模块 --------------------------------------------- */
.data-card {
  position: relative;
  padding: 22px;
  background: rgba(10, 39, 64, 0.72);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}
.data-card::before {
  content: "";
  position: absolute;
  top: -1px; left: -1px; right: -1px;
  height: 2px;
  background: linear-gradient(90deg, var(--c-orange), var(--c-amber) 55%, transparent);
}

.stat { display: flex; flex-direction: column; gap: 6px; }

.stat-number {
  font-family: var(--font-cond);
  font-size: clamp(40px, 5.4vw, 66px);
  font-weight: 700;
  line-height: 0.95;
  letter-spacing: -0.02em;
  color: var(--c-mist);
}
.stat-number--accent { color: var(--c-orange); }

.stat-label {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-grayblue);
}

.data-label {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: var(--c-grayblue);
  text-transform: uppercase;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 9px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--c-grayblue);
}
.tag--cyan { color: var(--c-cyan); border-color: rgba(47, 209, 220, 0.42); }
.tag--orange {
  color: var(--c-orange);
  border-color: rgba(255, 106, 26, 0.48);
  background: var(--tint-orange);
}

/* 10. 图片容器 -------------------------------------------- */
.media-frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background: linear-gradient(160deg, var(--c-steel), var(--c-ink));
  border: 1px solid var(--line);
  border-radius: var(--radius);
}
.media-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.86) contrast(1.06) brightness(0.9);
}
.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(180deg, rgba(5, 25, 43, 0.16), rgba(2, 10, 18, 0.64)),
    radial-gradient(120% 80% at 82% 0%, rgba(47, 209, 220, 0.16), transparent 62%);
}
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--square { aspect-ratio: 1 / 1; }

.media-caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--c-grayblue);
}

/* 11. 折叠组 ---------------------------------------------- */
.accordion { border-top: 1px solid var(--line); }
.accordion-item { border-bottom: 1px solid var(--line); }
.accordion-heading { font-size: inherit; font-weight: 400; margin: 0; }

.accordion-trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  width: 100%;
  padding: 18px 4px;
  background: transparent;
  border: 0;
  color: var(--c-mist);
  font-size: 17px;
  font-weight: 700;
  text-align: left;
  cursor: pointer;
  transition: background var(--dur) var(--ease), color var(--dur) var(--ease);
}
.accordion-trigger:hover { background: var(--tint-cyan); color: var(--c-cyan); }

.accordion-sign { position: relative; flex: 0 0 14px; height: 14px; }
.accordion-sign::before,
.accordion-sign::after {
  content: "";
  position: absolute;
  background: var(--c-orange);
  transition: transform var(--dur) var(--ease);
}
.accordion-sign::before { left: 0; right: 0; top: 6.5px; height: 1.5px; }
.accordion-sign::after { top: 0; bottom: 0; left: 6.5px; width: 1.5px; }
.accordion-trigger[aria-expanded="true"] .accordion-sign::after { transform: scaleY(0); }

.accordion-panel {
  padding: 0 4px 22px;
  font-size: 16px;
  line-height: 1.78;
  color: var(--c-grayblue);
}
.accordion-panel[hidden] { display: none; }

/* 12. 筛选标签 -------------------------------------------- */
.filter-bar {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 8px;
  scrollbar-width: none;
}
.filter-bar::-webkit-scrollbar { display: none; }

.filter-chip {
  flex: 0 0 auto;
  padding: 8px 14px;
  background: transparent;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--c-grayblue);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  cursor: pointer;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease),
              background var(--dur) var(--ease);
}
.filter-chip:hover { border-color: var(--c-cyan); color: var(--c-cyan); }
.filter-chip[aria-pressed="true"] {
  border-color: var(--c-orange);
  background: var(--tint-orange);
  color: var(--c-orange);
}

/* 13. 面包屑与长文 ---------------------------------------- */
.breadcrumbs { padding: 22px 0 0; }

.breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: var(--c-grayblue);
}

.breadcrumb-item { display: inline-flex; align-items: center; gap: 8px; }
.breadcrumb-item + .breadcrumb-item::before {
  content: "/";
  color: var(--c-steel);
}

.breadcrumb-link {
  color: var(--c-grayblue);
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}
.breadcrumb-link:hover { color: var(--c-cyan); }
.breadcrumb-link[aria-current="page"] { color: var(--c-mist); }

.prose {
  max-width: 42em;
  font-size: 17px;
  line-height: 1.78;
  color: var(--c-mist);
}
.prose > * + * { margin-top: 1.1em; }
.prose h2 { font-size: 28px; margin-top: 2.2em; }
.prose h3 { font-size: 20px; margin-top: 1.8em; }
.prose ul,
.prose ol { padding-left: 1.3em; }
.prose ul { list-style: disc; }
.prose ol { list-style: decimal; }
.prose li + li { margin-top: 0.45em; }
.prose a { color: var(--c-cyan); text-decoration: underline; text-underline-offset: 3px; }
.prose--wide { max-width: 52em; }

.section--paper .prose { color: #1F3B4C; }
.section--paper .prose h2,
.section--paper .prose h3 { color: var(--c-layer); }
.section--paper .prose a { color: var(--c-steel); }

/* 14. 显现动效 -------------------------------------------- */
.has-js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity var(--dur) var(--ease), transform var(--dur) var(--ease);
}
.has-js [data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* 15. 降低动效 -------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
  html { scroll-behavior: auto; }
  .has-js [data-reveal] { opacity: 1; transform: none; }
  .scroll-progress { transition: none; }
}