/* ============================================================
   YABO看台 · /assets/site.css
   01 重置 / 02 设计变量 / 03 基础排版 / 04 通用组件
   05 页头 / 06 页脚 / 07 动效与可见性 / 08 响应式与偏好
   ============================================================ */

/* 01 重置 */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body, h1, h2, h3, h4, p, ul, ol, figure, blockquote, dl, dd { margin: 0; }
ul, ol { padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }
table { border-collapse: collapse; width: 100%; }
main { display: block; }

/* 02 设计变量 */
:root {
  --ink-950: #020A08;
  --ink-900: #071C17;
  --ink-800: #0C2A22;
  --ink-700: #123F33;
  --cyan: #3DF5C8;
  --cyan-soft: #9BE8D6;
  --orange: #FF7A2F;
  --paper: #E8F4EF;
  --line: #2F5B4C;

  --text: var(--paper);
  --text-dim: #9BE8D6;
  --text-mute: #86B3A3;

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

  --wrap: 1220px;
  --gutter: clamp(18px, 4vw, 56px);
  --cut: 14px;
  --cut-lg: 24px;
  --ease: cubic-bezier(.22, .61, .36, 1);
  --gap: clamp(14px, 2vw, 24px);
}

/* 03 基础排版 */
body {
  background: var(--ink-900);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: clamp(16px, 1.02vw, 17.5px);
  line-height: 1.75;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
h1, h2, h3, h4 { font-family: var(--font-serif); font-weight: 900; line-height: 1.18; letter-spacing: -.02em; }
h1 { font-size: clamp(34px, 4.2vw, 60px); }
h2 { font-size: clamp(26px, 3vw, 40px); }
h3 { font-size: clamp(20px, 2vw, 26px); font-weight: 700; }
p { color: var(--text-dim); }
strong { color: var(--paper); font-weight: 700; }
::selection { background: var(--cyan); color: var(--ink-950); }
.mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; letter-spacing: .06em; }
:focus-visible { outline: 2px solid var(--cyan); outline-offset: 3px; }
#main-content:focus-visible { outline-offset: -3px; }

.skip-link {
  position: fixed;
  left: var(--gutter);
  top: -80px;
  z-index: 300;
  padding: 10px 18px;
  background: var(--orange);
  color: var(--ink-950);
  font-weight: 700;
  font-size: .85rem;
  letter-spacing: .04em;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 10px), calc(100% - 10px) 100%, 0 100%);
  transition: top .18s var(--ease);
}
.skip-link:focus { top: 12px; }

/* 04 通用组件 */
.container { width: 100%; max-width: var(--wrap); margin-inline: auto; padding-inline: var(--gutter); }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .5em;
  padding: .7em 1.15em;
  font-family: var(--font-sans);
  font-size: .88rem;
  font-weight: 700;
  letter-spacing: .03em;
  line-height: 1.2;
  color: var(--paper);
  background: var(--ink-800);
  border: 1px solid var(--line);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--cut)), calc(100% - var(--cut)) 100%, 0 100%);
  transition: background-color .18s var(--ease), border-color .18s var(--ease), color .18s var(--ease), filter .18s var(--ease);
}
.btn--signal { background: var(--orange); border-color: var(--orange); color: var(--ink-950); }
.btn--signal:hover { filter: brightness(1.1); }
.btn--ghost { background: transparent; border-color: var(--line); color: var(--cyan-soft); }
.btn--ghost:hover { border-color: var(--cyan); color: var(--cyan); }
.btn--block { width: 100%; }

.section { position: relative; padding-block: clamp(48px, 7vw, 96px); }
.section--band { background: var(--ink-800); border-block: 1px solid var(--line); }
.section__head { display: grid; gap: 10px; margin-bottom: clamp(20px, 3vw, 36px); }
.section__index { font-family: var(--font-mono); font-size: .72rem; letter-spacing: .24em; color: var(--cyan); text-transform: uppercase; }
.section__title { font-size: clamp(26px, 3vw, 40px); }
.section__lead { max-width: 32em; color: var(--text-dim); }

.grid { display: grid; gap: var(--gap); }
.grid--2 { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.grid--3 { grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }
.grid--asym { grid-template-columns: 1fr; }
.stack { display: grid; gap: var(--gap); }
.divider {
  height: 1px; border: 0; margin-block: clamp(24px, 4vw, 44px);
  background: repeating-linear-gradient(90deg, var(--line) 0 6px, transparent 6px 12px);
}

.panel {
  position: relative;
  background: var(--ink-800);
  border: 1px solid var(--line);
  padding: clamp(18px, 2vw, 26px);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 18px), calc(100% - 18px) 100%, 0 100%);
  transition: border-color .18s var(--ease);
}
.panel:hover { border-color: rgba(61, 245, 200, .55); }
.panel--entry { box-shadow: inset 3px 0 0 var(--orange); border-color: rgba(61, 245, 200, .3); }
.panel__label { display: block; font-family: var(--font-mono); font-size: .7rem; letter-spacing: .2em; color: var(--cyan); margin-bottom: 8px; }
.panel__title { font-family: var(--font-serif); font-weight: 700; font-size: 1.15rem; letter-spacing: -.01em; color: var(--paper); margin-bottom: 6px; }
.panel__meta { font-family: var(--font-mono); font-size: .72rem; letter-spacing: .1em; color: var(--text-mute); }

.chip {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 4px 10px;
  font-family: var(--font-mono); font-size: .68rem; letter-spacing: .14em;
  color: var(--text-dim);
  background: rgba(18, 63, 51, .6);
  border: 1px solid var(--line);
}
.chip--cyan { color: var(--cyan); border-color: rgba(61, 245, 200, .5); }
.chip--signal { color: var(--orange); border-color: rgba(255, 122, 47, .55); }

.figure { display: grid; gap: 10px; margin: 0; }
.figure__frame {
  position: relative; overflow: hidden;
  aspect-ratio: 16 / 9;
  background: linear-gradient(150deg, var(--ink-700), var(--ink-950));
  border: 1px solid var(--line);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--cut-lg)), calc(100% - var(--cut-lg)) 100%, 0 100%);
}
.figure__frame::after {
  content: ""; position: absolute; inset: 0; pointer-events: none;
  background:
    radial-gradient(120% 90% at 78% 10%, rgba(61, 245, 200, .16), transparent 62%),
    linear-gradient(180deg, transparent 42%, rgba(2, 10, 8, .82));
}
.figure__img { width: 100%; height: 100%; object-fit: cover; filter: saturate(.9) brightness(.86); }
.figure__caption { font-size: .78rem; letter-spacing: .04em; color: var(--text-mute); }

.breadcrumb { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; font-family: var(--font-mono); font-size: .72rem; letter-spacing: .12em; color: var(--text-mute); }
.breadcrumb__link { color: var(--text-dim); transition: color .18s var(--ease); }
.breadcrumb__link:hover { color: var(--cyan); }
.breadcrumb__sep { color: var(--line); }
.breadcrumb__current { color: var(--cyan); }

.prose { max-width: 36em; font-size: 1.02rem; line-height: 1.85; color: var(--text-dim); }
.prose > * + * { margin-top: 1.1em; }
.prose h2 { margin-top: 1.8em; font-size: clamp(22px, 2.2vw, 30px); color: var(--paper); }
.prose h3 { margin-top: 1.5em; font-size: clamp(18px, 1.6vw, 22px); color: var(--paper); }
.prose strong { color: var(--paper); }
.prose a { color: var(--cyan); text-decoration: underline; text-underline-offset: 3px; }
.prose ul { display: grid; gap: .5em; }
.prose ul li { position: relative; padding-left: 1.1em; }
.prose ul li::before { content: ""; position: absolute; left: 0; top: .78em; width: 8px; height: 1px; background: var(--cyan); }

.meter { position: relative; height: 6px; background: var(--ink-700); border: 1px solid var(--line); overflow: hidden; }
.meter__fill { display: block; height: 100%; width: var(--v, 60%); background: linear-gradient(90deg, var(--cyan), rgba(61, 245, 200, .12)); }

/* 05 页头 */
.site-header {
  position: sticky;
  top: 0;
  z-index: 120;
  background: linear-gradient(180deg, rgba(2, 10, 8, .72), rgba(2, 10, 8, 0));
  border-bottom: 1px solid transparent;
  transition: background-color .22s var(--ease), border-color .22s var(--ease), backdrop-filter .22s var(--ease);
}
.site-header[data-scrolled="true"] {
  background: rgba(7, 28, 23, .97);
  border-bottom-color: var(--line);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}
.progress { position: absolute; left: 0; right: 0; bottom: 0; height: 1px; background: rgba(47, 91, 76, .55); overflow: hidden; }
.progress__bar {
  display: block; width: 100%; height: 100%;
  background: linear-gradient(90deg, var(--cyan), var(--orange));
  transform: scaleX(var(--p, 0));
  transform-origin: 0 50%;
}

.header__inner {
  display: flex;
  align-items: center;
  gap: clamp(10px, 2vw, 28px);
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding: 12px var(--gutter);
  min-height: 66px;
}

.brand { display: inline-flex; align-items: center; gap: 10px; flex: 0 0 auto; }
.brand__mark {
  display: grid; place-items: center;
  width: 38px; height: 38px;
  font-family: var(--font-mono); font-size: .82rem; font-weight: 700; letter-spacing: .04em;
  color: var(--ink-950);
  background: var(--cyan);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 12px), calc(100% - 12px) 100%, 0 100%);
}
.brand__text { display: flex; flex-direction: column; line-height: 1.14; }
.brand__name { font-family: var(--font-serif); font-weight: 900; font-size: 1.08rem; letter-spacing: -.01em; color: var(--paper); }
.brand__tag { font-size: .66rem; letter-spacing: .18em; color: var(--cyan-soft); }
.brand--footer .brand__mark { background: var(--ink-700); color: var(--cyan); border: 1px solid rgba(61, 245, 200, .55); clip-path: none; }

.header__status { display: none; align-items: center; gap: 8px; font-size: .7rem; letter-spacing: .14em; color: var(--text-mute); }
.header__status-dot {
  width: 7px; height: 7px; border-radius: 50%;
  background: var(--orange);
  box-shadow: 0 0 0 3px rgba(255, 122, 47, .16);
  animation: statusPulse 2.6s var(--ease) infinite;
}
@keyframes statusPulse { 0%, 70%, 100% { opacity: 1; } 85% { opacity: .35; } }

.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  margin-left: auto;
  padding: 9px 12px;
  font-size: .76rem;
  font-weight: 700;
  letter-spacing: .16em;
  color: var(--paper);
  border: 1px solid var(--line);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 10px), calc(100% - 10px) 100%, 0 100%);
  transition: border-color .18s var(--ease), color .18s var(--ease);
}
.nav-toggle:hover { border-color: var(--cyan); color: var(--cyan); }
.nav-toggle__icon { display: flex; flex-direction: column; justify-content: center; gap: 4px; width: 18px; height: 14px; }
.nav-toggle__bar { display: block; width: 100%; height: 2px; background: currentColor; transition: transform .2s var(--ease), opacity .2s var(--ease); }
.site-header[data-open="true"] .nav-toggle { border-color: var(--orange); color: var(--orange); }
.site-header[data-open="true"] .nav-toggle__bar:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.site-header[data-open="true"] .nav-toggle__bar:nth-child(2) { opacity: 0; }
.site-header[data-open="true"] .nav-toggle__bar:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

.site-nav { display: none; }
.site-nav__list { display: flex; flex-direction: column; gap: 2px; }
.site-nav__item { display: flex; }
.site-nav__link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  padding: 12px 0;
  width: 100%;
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-dim);
  border-bottom: 1px solid rgba(47, 91, 76, .5);
  transition: color .18s var(--ease);
}
.site-nav__link:hover { color: var(--cyan); }
.site-nav__index { font-size: .64rem; letter-spacing: .1em; color: rgba(61, 245, 200, .55); }
.site-nav__actions { display: flex; flex-direction: column; gap: 10px; padding-top: 6px; }
.site-nav__actions .btn { width: 100%; }

@media (min-width: 981px) {
  .nav-toggle { display: none; }
  .header__status { display: inline-flex; margin-left: auto; }
  .site-nav { display: flex; align-items: center; gap: clamp(10px, 1.4vw, 22px); margin-left: clamp(4px, 1vw, 12px); }
  .site-nav__list { flex-direction: row; align-items: center; gap: clamp(8px, 1.1vw, 18px); }
  .site-nav__item { display: block; }
  .site-nav__link {
    width: auto;
    padding: 8px 2px;
    font-size: .88rem;
    border-bottom: 0;
  }
  .site-nav__link[aria-current="page"] { color: var(--cyan); }
  .site-nav__link[aria-current="page"]::after {
    content: "";
    position: absolute;
    left: 0; right: 0; bottom: 0;
    height: 2px;
    background: var(--orange);
  }
  .site-nav__link[aria-current="page"] .site-nav__index { color: var(--orange); }
  .site-nav__actions { flex-direction: row; padding-top: 0; padding-left: clamp(6px, 1vw, 14px); border-left: 1px solid var(--line); }
  .site-nav__actions .btn { width: auto; }
}
@media (min-width: 981px) and (max-width: 1180px) {
  .site-nav__actions .btn--ghost { display: none; }
}
@media (max-width: 980px) {
  .site-header { position: sticky; }
  .site-nav {
    position: absolute;
    left: 0; right: 0; top: 100%;
    display: none;
    flex-direction: column;
    gap: 14px;
    padding: 16px var(--gutter) 26px;
    background: var(--ink-800);
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--cyan);
    box-shadow: 0 24px 44px rgba(2, 10, 8, .62);
    max-height: calc(100vh - 66px);
    overflow-y: auto;
  }
  .site-header[data-open="true"] .site-nav { display: flex; }
  .site-nav__link[aria-current="page"] { color: var(--cyan); border-bottom-color: var(--orange); }
  .site-nav__link[aria-current="page"] .site-nav__index { color: var(--orange); }
}

/* 06 页脚 */
.site-footer {
  position: relative;
  margin-top: clamp(48px, 8vw, 104px);
  background: var(--ink-950);
  color: var(--text-dim);
  border-top: 1px solid var(--line);
}
.footer__scan {
  position: absolute; left: 0; right: 0; top: -1px; height: 2px;
  background: repeating-linear-gradient(90deg, var(--cyan) 0 2px, transparent 2px 16px);
  opacity: .55;
}
.footer__top {
  display: grid;
  gap: clamp(28px, 4vw, 52px);
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding: clamp(36px, 5vw, 68px) var(--gutter) 0;
}
.footer__brand { display: grid; gap: 16px; align-content: start; }
.footer__summary { max-width: 30em; font-size: .95rem; color: var(--cyan-soft); }
.footer__contact { display: grid; gap: 8px; }
.footer__contact-row { display: grid; grid-template-columns: 3.2em 1fr; gap: 10px; align-items: baseline; font-size: .92rem; }
.footer__contact-key { font-size: .68rem; letter-spacing: .18em; color: var(--cyan); }
.footer__contact-val { color: var(--paper); word-break: break-word; }
.footer__note {
  max-width: 34em;
  padding-left: 12px;
  font-size: .78rem;
  line-height: 1.7;
  color: var(--text-mute);
  border-left: 2px solid var(--orange);
}
.footer__grid { display: grid; gap: clamp(20px, 3vw, 34px); grid-template-columns: repeat(auto-fit, minmax(130px, 1fr)); align-content: start; }
.footer__col { display: grid; gap: 12px; align-content: start; }
.footer__col-title { font-family: var(--font-mono); font-size: .72rem; font-weight: 500; letter-spacing: .22em; color: var(--cyan); }
.footer__links { display: grid; gap: 10px; }
.footer__link {
  display: inline-block;
  font-size: .92rem;
  color: var(--text-dim);
  border-bottom: 1px solid transparent;
  transition: color .18s var(--ease), border-color .18s var(--ease);
}
.footer__link:hover { color: var(--cyan); border-bottom-color: var(--cyan); }
.footer__bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 24px;
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  margin-top: clamp(28px, 4vw, 48px);
  padding: 18px var(--gutter) 30px;
  border-top: 1px solid rgba(47, 91, 76, .65);
  font-size: .76rem;
  letter-spacing: .06em;
  color: var(--text-mute);
}
.footer__legal { color: var(--text-mute); }
.footer__end { font-size: .7rem; letter-spacing: .22em; color: rgba(61, 245, 200, .75); }

@media (min-width: 880px) {
  .footer__top { grid-template-columns: minmax(0, 1.05fr) minmax(0, 1.25fr); }
}

/* 07 动效与可见性 */
html.js-ready [data-reveal] { opacity: 0; transform: translateY(6px); }
html.js-ready [data-reveal].is-visible { opacity: 1; transform: none; transition: opacity .22s var(--ease), transform .22s var(--ease); }

/* 08 响应式与偏好 */
@media (max-width: 640px) {
  .brand__tag { display: none; }
  .header__inner { min-height: 60px; }
  .footer__contact-row { grid-template-columns: 1fr; gap: 2px; }
  .panel { clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--cut)), calc(100% - var(--cut)) 100%, 0 100%); }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }
  html.js-ready [data-reveal] { opacity: 1; transform: none; }
  .header__status-dot { animation: none; }
  .progress__bar { transition: none; }
}

@media print {
  .site-header, .site-footer, .skip-link { display: none; }
  body { background: #fff; color: #111; }
  .panel, .figure__frame { border: 1px solid #999; background: #fff; clip-path: none; }
}