/* ============================================================
   OPEBET ARENA — /assets/site.css
   共享层：reset · tokens · 中文排版 · 刊头 · 页脚 · 通用组件
   ============================================================ */

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

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

body, h1, h2, h3, h4, h5, p, ul, ol, li, figure, dl, dt, dd, blockquote { margin: 0; padding: 0; }
ul, ol { list-style: none; }
img, svg { display: block; max-width: 100%; }
button { font: inherit; color: inherit; background: none; border: 0; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; width: 100%; }

/* ---------- tokens ---------- */
:root {
  --ink: #070B16;
  --ink-2: #0E1730;
  --panel: #16244A;
  --red: #E4442F;
  --cyan: #00E5D0;
  --gold: #D8B36A;
  --paper: #F2E8D8;
  --body: #C3CCE0;
  --fog: #8E9CBB;
  --line: #26314F;
  --white: #F7F9FF;
  --dim: #5C6A8C;

  --shell: 1240px;
  --gut: clamp(18px, 4vw, 44px);

  --font-head: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-body: var(--font-head);
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;

  --t: 220ms;
  --ease: cubic-bezier(.22, .61, .36, 1);
}

/* ---------- 基础与中文排版 ---------- */
body {
  min-height: 100vh;
  overflow-x: hidden;
  background-color: var(--ink);
  background-image:
    radial-gradient(900px 540px at 10% -10%, rgba(0, 229, 208, .085), transparent 62%),
    radial-gradient(780px 500px at 98% 4%, rgba(228, 68, 47, .10), transparent 66%);
  background-attachment: fixed;
  background-repeat: no-repeat;
  color: var(--body);
  font: 400 17px/1.75 var(--font-body);
  letter-spacing: .01em;
}

@media (max-width: 640px) {
  body { font-size: 16px; }
}

h1, h2, h3, h4 {
  font-family: var(--font-head);
  font-weight: 900;
  color: var(--white);
  line-height: 1.16;
  letter-spacing: -.022em;
}

p + p { margin-top: 1.2em; }

::selection { background: rgba(0, 229, 208, .3); color: var(--white); }

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

#main-content { scroll-margin-top: clamp(96px, 12vw, 150px); }

/* ---------- 容器 ---------- */
.shell {
  width: min(100% - (var(--gut) * 2), var(--shell));
  margin-inline: auto;
}

/* ---------- 跳转链接 ---------- */
.skip-link {
  position: fixed;
  left: 14px;
  top: -120px;
  z-index: 200;
  padding: 13px 20px;
  background: var(--cyan);
  color: var(--ink);
  font: 700 14px/1 var(--font-body);
  letter-spacing: .06em;
  border-radius: 2px;
  transition: top .18s var(--ease);
}
.skip-link:focus { top: 14px; }

/* ---------- 阅读进度 ---------- */
.scroll-progress {
  position: fixed;
  inset: 0 0 auto 0;
  height: 2px;
  z-index: 150;
  background: rgba(38, 49, 79, .55);
  pointer-events: none;
}
.scroll-progress__bar {
  display: block;
  height: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--red), var(--gold) 55%, var(--cyan));
}

/* ============================================================
   刊头
   ============================================================ */
.masthead {
  position: sticky;
  top: 0;
  z-index: 120;
  background: rgba(7, 11, 22, .94);
  border-bottom: 1px solid var(--line);
  -webkit-backdrop-filter: blur(14px) saturate(1.25);
  backdrop-filter: blur(14px) saturate(1.25);
  transition: box-shadow var(--t) var(--ease), background var(--t) var(--ease);
}
.masthead.is-condensed {
  background: rgba(7, 11, 22, .975);
  box-shadow: 0 22px 46px -30px rgba(0, 0, 0, .95), 0 1px 0 rgba(0, 229, 208, .18);
}

.masthead__signal {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 1px;
  pointer-events: none;
  background: linear-gradient(90deg, transparent, rgba(216, 179, 106, .65), rgba(0, 229, 208, .55), transparent);
  animation: signal-breathe 6s ease-in-out infinite;
}
@keyframes signal-breathe {
  0%, 100% { opacity: .32; }
  50% { opacity: .85; }
}

.masthead__edge {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  max-height: 48px;
  padding-block: 12px;
  overflow: hidden;
  border-bottom: 1px solid rgba(38, 49, 79, .7);
  color: var(--dim);
  font: 600 11px/1 var(--font-mono);
  letter-spacing: .2em;
  text-transform: uppercase;
  transition: max-height .34s var(--ease), opacity .2s linear, padding .3s var(--ease);
}
.masthead__edge-item { white-space: nowrap; }
.masthead.is-condensed .masthead__edge {
  max-height: 0;
  padding-block: 0;
  opacity: 0;
  border-color: transparent;
}

.masthead__body { display: block; }

.masthead__plate {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding-block: clamp(14px, 2.2vw, 28px) clamp(10px, 1.6vw, 20px);
  transition: padding .3s var(--ease);
}
.masthead.is-condensed .masthead__plate { padding-block: 9px; }

.masthead__kicker {
  max-height: 24px;
  overflow: hidden;
  color: var(--fog);
  font-size: 12px;
  letter-spacing: .26em;
  text-transform: uppercase;
  transition: max-height .3s var(--ease), opacity .18s linear, margin .3s var(--ease);
}
.masthead.is-condensed .masthead__kicker {
  max-height: 0;
  margin: 0;
  opacity: 0;
}

.masthead__brand {
  display: inline-flex;
  align-items: baseline;
  gap: .34em;
  line-height: 1;
  color: var(--white);
  font-weight: 900;
  font-size: clamp(1.9rem, 5vw, 3.4rem);
  letter-spacing: -.03em;
  transition: font-size .3s var(--ease), color var(--t) var(--ease);
}
.masthead__brand-latin { font-family: var(--font-head); }
.masthead__brand-arena {
  color: var(--cyan);
  font-size: .72em;
  letter-spacing: -.015em;
}
.masthead__brand-cn {
  color: var(--gold);
  font-size: .27em;
  font-weight: 700;
  letter-spacing: .34em;
}
.masthead__brand:hover { color: var(--cyan); }
.masthead__brand:hover .masthead__brand-arena { color: var(--white); }
.masthead.is-condensed .masthead__brand { font-size: clamp(1.15rem, 2.4vw, 1.6rem); }

.masthead__navwrap {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  padding-block: 10px 13px;
  border-top: 1px solid rgba(38, 49, 79, .9);
}

.site-nav { flex: 1 1 auto; min-width: 0; }

.nav-list {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: clamp(14px, 2.6vw, 38px);
}
.nav-list__item { display: block; }

.nav-link {
  position: relative;
  display: inline-block;
  padding: 8px 2px;
  color: var(--body);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: .08em;
  transition: color var(--t) var(--ease);
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 1px;
  height: 1px;
  background: var(--cyan);
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform .26s var(--ease);
}
.nav-link:hover, .nav-link:focus-visible { color: var(--cyan); }
.nav-link:hover::after, .nav-link:focus-visible::after { transform: scaleX(1); }
.nav-link[aria-current="page"] { color: var(--white); }
.nav-link[aria-current="page"]::after {
  transform: scaleX(1);
  background: var(--red);
  height: 2px;
}

.masthead__cta {
  position: absolute;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 10px 18px;
  border: 1px solid var(--line);
  color: var(--body);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: .1em;
  transition: border-color var(--t) var(--ease), color var(--t) var(--ease), background var(--t) var(--ease);
}
.masthead__cta::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--red);
  box-shadow: 0 0 0 4px rgba(228, 68, 47, .18);
}
.masthead__cta:hover, .masthead__cta:focus-visible {
  border-color: var(--cyan);
  color: var(--cyan);
  background: rgba(0, 229, 208, .06);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  border: 1px solid var(--line);
  color: var(--body);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: .16em;
  cursor: pointer;
  transition: border-color var(--t) var(--ease), color var(--t) var(--ease);
}
.nav-toggle:hover { border-color: var(--cyan); color: var(--cyan); }
.nav-toggle__mark { position: relative; width: 16px; height: 10px; }
.nav-toggle__mark::before,
.nav-toggle__mark::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--cyan);
  transition: transform .24s var(--ease), top .24s var(--ease), bottom .24s var(--ease);
}
.nav-toggle__mark::before { top: 0; }
.nav-toggle__mark::after { bottom: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__mark::before { top: 4px; transform: rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__mark::after { bottom: 4px; transform: rotate(-45deg); }
.nav-toggle__text { white-space: nowrap; }

.masthead__strip {
  position: relative;
  z-index: 1;
  padding-block: 10px 12px;
  border-top: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(14, 23, 48, .92), rgba(7, 11, 22, .92));
}
.masthead__strip[hidden] { display: none; }

@media (max-width: 900px) {
  .masthead__navwrap {
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 10px;
  }
  .nav-toggle { display: inline-flex; order: 1; }
  .masthead__cta {
    position: static;
    transform: none;
    order: 2;
    padding: 9px 14px;
    font-size: 12px;
  }
  .masthead__cta::before { width: 5px; height: 5px; }

  .site-nav {
    order: 3;
    flex: 0 0 100%;
    display: none;
    min-width: 0;
    margin-top: 10px;
    border-top: 1px solid var(--line);
  }
  .site-nav[data-open="true"] { display: block; }

  .nav-list { flex-direction: column; align-items: stretch; gap: 0; }
  .nav-list__item { border-bottom: 1px solid rgba(38, 49, 79, .7); }
  .nav-list__item:last-child { border-bottom: 0; }
  .nav-link { display: block; padding: 15px 6px; font-size: 16px; }
  .nav-link::after { display: none; }
  .nav-link[aria-current="page"] {
    color: var(--cyan);
    box-shadow: inset 2px 0 0 var(--red);
    padding-left: 16px;
  }
}

/* ============================================================
   页脚
   ============================================================ */
.site-foot {
  position: relative;
  overflow: hidden;
  margin-top: clamp(56px, 8vw, 120px);
  padding-top: clamp(44px, 5.6vw, 82px);
  background: var(--ink-2);
  border-top: 1px solid var(--line);
  color: var(--fog);
  font-size: 15px;
}
.site-foot::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(216, 179, 106, .7), rgba(0, 229, 208, .55), transparent);
}
.site-foot__veil {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(38, 49, 79, .9) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(38, 49, 79, .9) 1px, transparent 1px);
  background-size: 96px 96px;
  opacity: .28;
  -webkit-mask-image: linear-gradient(to bottom, rgba(0, 0, 0, .85), transparent 82%);
  mask-image: linear-gradient(to bottom, rgba(0, 0, 0, .85), transparent 82%);
}

.site-foot__top {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 1.6fr);
  gap: clamp(28px, 4vw, 64px);
  padding-bottom: clamp(28px, 3.4vw, 48px);
  border-bottom: 1px solid var(--line);
}

.site-foot__wordmark {
  color: var(--white);
  font-size: clamp(1.5rem, 3vw, 2.1rem);
  font-weight: 900;
  line-height: 1;
  letter-spacing: -.02em;
}
.site-foot__wordmark span { color: var(--cyan); }

.site-foot__tagline {
  margin-top: 16px;
  color: var(--paper);
  font-size: 17px;
  letter-spacing: .02em;
}
.site-foot__region {
  margin-top: 12px;
  max-width: 44ch;
  color: var(--fog);
  font-size: 14px;
  line-height: 1.72;
}

.site-foot__cols {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(18px, 3vw, 40px);
}
.foot-col__title {
  margin-bottom: 16px;
  color: var(--gold);
  font: 700 12px/1 var(--font-mono);
  letter-spacing: .2em;
  text-transform: uppercase;
}
.foot-col__list li + li { margin-top: 11px; }

.foot-link {
  position: relative;
  display: inline-block;
  color: var(--body);
  font-size: 15px;
  letter-spacing: .04em;
  transition: color var(--t) var(--ease);
}
.foot-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -3px;
  width: 100%;
  height: 1px;
  background: var(--cyan);
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform .24s var(--ease);
}
.foot-link:hover, .foot-link:focus-visible { color: var(--cyan); }
.foot-link:hover::after, .foot-link:focus-visible::after { transform: scaleX(1); }

.site-foot__contact {
  position: relative;
  z-index: 1;
  display: flex;
  flex-wrap: wrap;
  gap: 12px clamp(18px, 3vw, 48px);
  padding-block: clamp(20px, 2.6vw, 32px);
  border-bottom: 1px solid var(--line);
}
.site-foot__contactitem {
  display: flex;
  align-items: baseline;
  gap: 10px;
  color: var(--body);
  font-size: 14.5px;
  letter-spacing: .02em;
}
.site-foot__label {
  color: var(--dim);
  font: 700 11px/1 var(--font-mono);
  letter-spacing: .2em;
  text-transform: uppercase;
}

.site-foot__legal {
  position: relative;
  z-index: 1;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 26px;
  padding-block: clamp(18px, 2.4vw, 28px) clamp(26px, 3.4vw, 48px);
  color: var(--dim);
  font-size: 13px;
}
.site-foot__copy { letter-spacing: .02em; }
.site-foot__route {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 10px;
}
.foot-link--minor {
  color: var(--dim);
  font-size: 13px;
}
.foot-link--minor::after { display: none; }
.foot-link--minor:hover, .foot-link--minor:focus-visible { color: var(--cyan); }

@media (max-width: 900px) {
  .site-foot__top { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .site-foot__cols { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .site-foot__legal { flex-direction: column; align-items: flex-start; }
}
@media (max-width: 420px) {
  .site-foot__cols { grid-template-columns: 1fr; }
}

/* ============================================================
   通用按钮
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .6em;
  padding: 14px 24px;
  border: 1px solid var(--line);
  border-radius: 2px;
  background: transparent;
  color: var(--body);
  font: 700 15px/1 var(--font-body);
  letter-spacing: .06em;
  cursor: pointer;
  transition: border-color var(--t) var(--ease), color var(--t) var(--ease), background var(--t) var(--ease), transform var(--t) var(--ease);
}
.btn:hover { transform: translateY(-2px); }
.btn--primary {
  background: var(--red);
  border-color: var(--red);
  color: #fff;
}
.btn--primary:hover { background: #F04E38; border-color: #F04E38; }
.btn--ghost { color: var(--body); }
.btn--ghost:hover { border-color: var(--cyan); color: var(--cyan); background: rgba(0, 229, 208, .06); }
.btn--paper {
  background: var(--paper);
  border-color: var(--paper);
  color: #141B2C;
}
.btn--paper:hover { background: #FFF7EA; border-color: #FFF7EA; }

/* ============================================================
   面包屑
   ============================================================ */
.crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  color: var(--fog);
  font-size: 13px;
  letter-spacing: .06em;
}
.crumbs a { color: var(--fog); transition: color var(--t) var(--ease); }
.crumbs a:hover { color: var(--cyan); }
.crumbs__sep { color: #3A4768; }
.crumbs [aria-current="page"] { color: var(--body); }

/* ============================================================
   正文容器
   ============================================================ */
.prose {
  max-width: 66ch;
  color: var(--body);
  font-size: 17px;
  line-height: 1.78;
}
.prose > * + * { margin-top: 1.2em; }
.prose h2 {
  font-size: clamp(1.5rem, 2.6vw, 2rem);
  font-weight: 900;
}
.prose h3 {
  font-size: clamp(1.15rem, 1.9vw, 1.35rem);
  font-weight: 800;
}
.prose strong { color: var(--white); font-weight: 700; }
.prose a {
  color: var(--cyan);
  border-bottom: 1px solid rgba(0, 229, 208, .38);
}
.prose a:hover { border-bottom-color: var(--cyan); }
.prose ul li {
  position: relative;
  padding-left: 20px;
}
.prose ul li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .78em;
  width: 9px;
  height: 1px;
  background: var(--gold);
}

/* ============================================================
   网格
   ============================================================ */
.grid {
  display: grid;
  gap: clamp(18px, 2.4vw, 32px);
}
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--index {
  grid-template-columns: minmax(210px, 280px) minmax(0, 1fr);
  align-items: start;
}

@media (max-width: 1023px) {
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--index { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 639px) {
  .grid--2, .grid--3 { grid-template-columns: minmax(0, 1fr); }
}

/* ============================================================
   数据面板与存档卡
   ============================================================ */
.panel {
  position: relative;
  padding: clamp(18px, 2.2vw, 28px);
  background: rgba(22, 36, 74, .5);
  border: 1px solid var(--line);
  transition: transform var(--t) var(--ease), border-color var(--t) var(--ease), background var(--t) var(--ease);
}
.panel--interactive:hover,
.panel--interactive:focus-within {
  transform: translateY(-4px);
  border-color: var(--cyan);
  background: rgba(22, 36, 74, .74);
}
.panel__meta {
  color: var(--gold);
  font: 700 12px/1 var(--font-mono);
  letter-spacing: .18em;
  text-transform: uppercase;
}
.panel__title {
  margin-top: 12px;
  color: var(--white);
  font-size: clamp(1.1rem, 2vw, 1.45rem);
  font-weight: 800;
  line-height: 1.32;
  letter-spacing: -.012em;
}
.panel__body {
  margin-top: 10px;
  color: var(--body);
  font-size: 15px;
  line-height: 1.72;
}

.paper-card {
  padding: clamp(20px, 2.4vw, 34px);
  background: var(--paper);
  border: 1px solid #D6C9B2;
  border-radius: 2px;
  color: #151C2E;
  font-size: 15.5px;
  line-height: 1.72;
}
.paper-card .panel__meta,
.paper-card .section__num { color: #8A6F34; }
.paper-card .panel__title,
.paper-card h2,
.paper-card h3 { color: #101728; }
.paper-card a { color: #A13A1F; border-bottom: 1px solid rgba(161, 58, 31, .35); }
.paper-card .mono { color: #6B5A32; }

/* ============================================================
   图片容器（页面阶段放置 <img>）
   ============================================================ */
.media-frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background: var(--ink-2);
  border: 1px solid var(--line);
}
.media-frame__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: contrast(1.08) saturate(.9);
}
.media-frame__tag {
  position: absolute;
  left: 0;
  top: 0;
  padding: 8px 14px;
  background: var(--red);
  color: #fff;
  font: 700 11px/1 var(--font-mono);
  letter-spacing: .18em;
  text-transform: uppercase;
}
.media-frame__caption {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 26px 16px 12px;
  background: linear-gradient(to top, rgba(7, 11, 22, .94), transparent);
  color: var(--body);
  font-size: 13px;
  letter-spacing: .04em;
}
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--cut { clip-path: polygon(0 0, 100% 0, 100% 82%, 0 100%); }
.media-frame--scan::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: repeating-linear-gradient(to bottom, rgba(242, 232, 216, .05) 0 1px, transparent 1px 4px);
}

@media (max-width: 639px) {
  .media-frame { aspect-ratio: 4 / 3; }
  .media-frame--tall { aspect-ratio: 3 / 4; }
  .media-frame--wide { aspect-ratio: 16 / 9; }
}

/* ============================================================
   章节骨架
   ============================================================ */
.section {
  position: relative;
  padding-block: clamp(44px, 6.4vw, 96px);
}
.section--tight { padding-block: clamp(26px, 4vw, 56px); }

.section__num {
  display: inline-block;
  color: var(--gold);
  font: 700 12px/1 var(--font-mono);
  letter-spacing: .24em;
  text-transform: uppercase;
}
.section__title {
  margin-top: 14px;
  color: var(--white);
  font-size: clamp(1.8rem, 3.6vw, 3rem);
  font-weight: 900;
  line-height: 1.12;
  letter-spacing: -.026em;
}
.section__lede {
  margin-top: 16px;
  max-width: 60ch;
  color: var(--fog);
  font-size: 17px;
  line-height: 1.74;
}
.section__rule {
  margin-top: clamp(20px, 2.6vw, 34px);
  height: 1px;
  background: var(--line);
  border: 0;
}
.watermark {
  position: absolute;
  right: 0;
  top: clamp(20px, 4vw, 54px);
  pointer-events: none;
  user-select: none;
  color: rgba(38, 49, 79, .5);
  font: 900 clamp(4rem, 12vw, 10rem)/1 var(--font-mono);
  letter-spacing: -.06em;
}

/* ============================================================
   侧边索引 / 时间轴
   ============================================================ */
.index-rail { border-top: 1px solid var(--line); }
.index-rail__item a {
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: baseline;
  gap: 12px;
  padding: 14px 10px 14px 0;
  border-bottom: 1px solid var(--line);
  color: var(--fog);
  font-size: 15px;
  transition: color var(--t) var(--ease), padding var(--t) var(--ease), background var(--t) var(--ease);
}
.index-rail__item .mono { color: var(--gold); font-size: 12px; }
.index-rail__item a:hover,
.index-rail__item a:focus-visible {
  padding-left: 12px;
  color: var(--white);
  background: rgba(22, 36, 74, .5);
}
.index-rail__item a.is-active,
.index-rail__item a[aria-current="true"] {
  padding-left: 12px;
  color: var(--cyan);
  box-shadow: inset 3px 0 0 var(--red);
}

/* ============================================================
   筛选 chips 与轮次轨道
   ============================================================ */
.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
.chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: 2px;
  background: rgba(22, 36, 74, .55);
  color: var(--body);
  font: 600 13px/1 var(--font-body);
  letter-spacing: .08em;
  cursor: pointer;
  transition: border-color var(--t) var(--ease), color var(--t) var(--ease), background var(--t) var(--ease);
}
.chip:hover { border-color: var(--cyan); color: var(--cyan); }
.chip[aria-pressed="true"],
.chip.is-active {
  border-color: var(--red);
  background: rgba(228, 68, 47, .16);
  color: var(--white);
}

.roundline {
  display: flex;
  gap: 10px;
  overflow-x: auto;
  scroll-behavior: smooth;
  padding-bottom: 10px;
  scrollbar-width: thin;
  scrollbar-color: var(--line) transparent;
}
.roundline::-webkit-scrollbar { height: 6px; }
.roundline::-webkit-scrollbar-thumb { background: var(--line); }
.roundline::-webkit-scrollbar-track { background: transparent; }

/* ============================================================
   折叠问答
   ============================================================ */
.accordion { border-top: 1px solid var(--line); }
.accordion__item { border-bottom: 1px solid var(--line); }
.accordion__trigger {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 20px;
  width: 100%;
  padding: 20px 0;
  color: var(--white);
  font: 700 17px/1.5 var(--font-body);
  letter-spacing: .01em;
  text-align: left;
  cursor: pointer;
  transition: color var(--t) var(--ease);
}
.accordion__trigger:hover,
.accordion__trigger:focus-visible { color: var(--cyan); }
.accordion__icon {
  position: relative;
  flex: 0 0 auto;
  width: 14px;
  height: 14px;
  margin-top: 5px;
}
.accordion__icon::before,
.accordion__icon::after {
  content: "";
  position: absolute;
  background: var(--cyan);
  transition: transform .26s var(--ease);
}
.accordion__icon::before { left: 0; right: 0; top: 6px; height: 1.5px; }
.accordion__icon::after { top: 0; bottom: 0; left: 6px; width: 1.5px; }
.accordion__item[data-open="true"] .accordion__icon::after { transform: scaleY(0); }
.accordion__panel {
  display: none;
  max-width: 72ch;
  padding: 0 0 22px;
  color: var(--body);
  font-size: 16px;
  line-height: 1.76;
}
.accordion__item[data-open="true"] .accordion__panel { display: block; }

/* ============================================================
   工具类
   ============================================================ */
.mono { font-family: var(--font-mono); letter-spacing: .04em; }
.kicker {
  color: var(--gold);
  font: 700 12px/1 var(--font-mono);
  letter-spacing: .22em;
  text-transform: uppercase;
}
.lede {
  color: var(--fog);
  font-size: clamp(1.05rem, 1.6vw, 1.25rem);
  line-height: 1.7;
}
.hr { height: 1px; background: var(--line); border: 0; }
.stack > * + * { margin-top: 16px; }
.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;
}

/* ============================================================
   动效降级
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
    scroll-behavior: auto !important;
  }
  .panel--interactive:hover,
  .panel--interactive:focus-within,
  .btn:hover { transform: none; }
}