/* 黑柏沟 · 2026
   风格基准：暖米白、衬线大标题、terracotta 强调、极简装饰
   移动优先；19px 正文，老年读者可切「大字」 */

:root{
  --bg:#F7F5F0;
  --bg-soft:#FDFCF9;
  --ink:#1F1E1D;
  --ink-2:#3A3835;
  --muted:#6B6760;
  --line:#E4E0D5;
  --accent:#C15F3C;
  --accent-ink:#8F4227;

  --serif:"Noto Serif SC","Source Han Serif SC","Songti SC","STSong","SimSun",serif;
  --sans:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Helvetica Neue",Arial,sans-serif;

  --fs-body:19px;
  --fs-small:15px;
  --fs-h1:44px;
  --fs-h2:32px;
  --fs-ch:40px;
  --fs-motto:20px;

  --measure:34em;
  --gap:72px;
  --pad:20px;
  --bar:52px;
}

html[data-fs="lg"]{
  --fs-body:22px;
  --fs-small:17px;
  --fs-h1:52px;
  --fs-h2:38px;
  --fs-ch:48px;
  --fs-motto:24px;
  --measure:30em;
}

*,*::before,*::after{box-sizing:border-box}

html{-webkit-text-size-adjust:100%}

body{
  margin:0;
  padding-top:var(--bar);
  background:var(--bg);
  color:var(--ink);
  font-family:var(--sans);
  font-size:var(--fs-body);
  line-height:1.85;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

img{display:block;max-width:100%;height:auto}
button{font:inherit;color:inherit}

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

/* ---------- 顶栏 ---------- */
.bar{
  position:fixed;inset:0 0 auto 0;z-index:40;
  height:var(--bar);
  background:rgba(247,245,240,.92);
  -webkit-backdrop-filter:saturate(1.2) blur(8px);
  backdrop-filter:saturate(1.2) blur(8px);
  border-bottom:1px solid transparent;
  transition:border-color .2s ease;
}
.bar.is-scrolled{border-bottom-color:var(--line)}
.bar-in{
  max-width:1080px;margin:0 auto;height:100%;
  padding:0 var(--pad);
  display:flex;align-items:center;justify-content:space-between;gap:12px;
}
.bar-title{
  font-family:var(--serif);font-size:15px;letter-spacing:.08em;color:var(--ink-2);
}
.fs{display:flex;gap:4px}
.fs button{
  min-width:52px;height:34px;padding:0 10px;
  border:1px solid var(--line);border-radius:4px;
  background:transparent;color:var(--muted);
  font-size:13px;letter-spacing:.06em;cursor:pointer;
}
.fs button[aria-pressed="true"]{
  border-color:var(--ink);color:var(--ink);
}
.fs button:focus-visible{outline:2px solid var(--accent);outline-offset:2px}

/* ---------- 封面 ---------- */
.cover{
  max-width:1080px;margin:0 auto;
  padding:calc(var(--gap) * .9) var(--pad) calc(var(--gap) * .6);
  text-align:center;
}
.eyebrow{
  margin:0 0 20px;
  font-size:var(--fs-small);letter-spacing:.18em;color:var(--muted);
}
.cover h1{
  margin:0;
  font-family:var(--serif);font-weight:300;
  font-size:var(--fs-h1);line-height:1.15;letter-spacing:.14em;
  text-indent:.14em;
}
.cover-sub{
  margin:18px 0 0;
  font-family:var(--serif);font-size:calc(var(--fs-body) * 1.05);
  letter-spacing:.24em;text-indent:.24em;color:var(--ink-2);
}
.cover-meta{
  margin:10px 0 0;
  font-size:var(--fs-small);letter-spacing:.1em;color:var(--muted);
}

/* ---------- 主视频 ---------- */
.film{
  max-width:1080px;margin:0 auto;
  padding:0 var(--pad) var(--gap);
}
.player{
  position:relative;overflow:hidden;border-radius:6px;
  background:#2B2926;aspect-ratio:16 / 9;
}
.player img{width:100%;height:100%;object-fit:cover}
.player::after{
  content:"";position:absolute;inset:0;
  background:linear-gradient(180deg,rgba(0,0,0,0) 55%,rgba(0,0,0,.35) 100%);
  pointer-events:none;
}
.play{
  position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);
  width:88px;height:88px;border-radius:50%;border:0;
  background:var(--accent);color:#fff;
  display:grid;place-items:center;cursor:pointer;
  box-shadow:0 10px 30px rgba(0,0,0,.25);
  transition:transform .18s ease,background .18s ease;
}
.play:hover{background:var(--accent-ink);transform:translate(-50%,-50%) scale(1.04)}
.play:focus-visible{outline:3px solid #fff;outline-offset:4px}
.play svg{width:34px;height:34px;fill:currentColor;margin-left:4px}
.player-meta{
  position:absolute;left:18px;bottom:14px;margin:0;
  font-size:14px;letter-spacing:.08em;color:rgba(255,255,255,.88);
}
.film-note{
  margin:16px auto 0;max-width:var(--measure);
  font-size:var(--fs-small);color:var(--muted);text-align:center;
}

/* ---------- 引言 ---------- */
.intro{
  max-width:1080px;margin:0 auto;
  padding:var(--gap) var(--pad);
  border-top:1px solid var(--line);
  text-align:center;
}
.label{
  margin:0 0 26px;
  font-size:var(--fs-small);letter-spacing:.2em;color:var(--muted);
}
.motto{
  margin:0 auto;max-width:36em;
  font-family:var(--serif);font-size:var(--fs-motto);
  line-height:2.1;letter-spacing:.12em;color:var(--ink);
}
.motto span{display:block}
.lead{
  margin:28px auto 0;max-width:var(--measure);
  text-align:left;color:var(--ink-2);
}
.lead:first-of-type{margin-top:40px}

/* ---------- 章节 ---------- */
.chapter{
  max-width:1080px;margin:0 auto;
  padding:var(--gap) var(--pad) 0;
  border-top:1px solid var(--line);
}
.ch-head{
  display:flex;align-items:baseline;gap:18px;
  max-width:var(--measure);margin:0 auto;
}
.ch-no{
  margin:0;
  font-family:var(--serif);font-size:calc(var(--fs-ch) * .86);
  line-height:1;color:var(--accent);letter-spacing:.02em;
}
.ch-name{
  margin:0;
  font-family:var(--serif);font-weight:300;
  font-size:var(--fs-ch);line-height:1.1;letter-spacing:.16em;
}
.ch-sub{
  max-width:var(--measure);margin:16px auto 0;
  font-size:var(--fs-small);letter-spacing:.14em;color:var(--muted);
}
.ch-text{
  max-width:var(--measure);margin:18px auto 0;color:var(--ink-2);
}

/* 图集：手机横滑带半张露出 */
.gallery{
  display:flex;gap:12px;overflow-x:auto;
  scroll-snap-type:x mandatory;
  margin:28px calc(var(--pad) * -1) 0;
  padding:0 var(--pad) 4px;
  scrollbar-width:none;
}
.gallery::-webkit-scrollbar{display:none}
.gallery figure{
  flex:0 0 86%;margin:0;scroll-snap-align:start;
  border-radius:6px;overflow:hidden;background:#EBE7DC;
}
.gallery img{
  width:100%;aspect-ratio:4 / 3;object-fit:cover;
  cursor:zoom-in;
}

.dots{
  display:flex;gap:7px;justify-content:center;
  margin:14px 0 0;height:8px;
}
.dots i{
  width:6px;height:6px;border-radius:50%;
  background:var(--line);transition:background .2s ease,transform .2s ease;
}
.dots i.on{background:var(--accent);transform:scale(1.25)}

/* ---------- 照片墙 ---------- */
.wall-sec{
  max-width:1080px;margin:0 auto;
  padding:var(--gap) var(--pad) 0;
  border-top:1px solid var(--line);
}
.wall-head{max-width:var(--measure);margin:0 auto 28px}
.wall-head h2{
  margin:0;font-family:var(--serif);font-weight:300;
  font-size:var(--fs-h2);letter-spacing:.14em;
}
.wall-head p{margin:8px 0 0;font-size:var(--fs-small);color:var(--muted);letter-spacing:.1em}
.wall{
  columns:2;column-gap:10px;
}
.wall figure{margin:0 0 10px;break-inside:avoid;border-radius:4px;overflow:hidden;background:#EBE7DC}
.wall img{width:100%;cursor:zoom-in}

/* ---------- 收尾 ---------- */
.end{
  max-width:1080px;margin:0 auto;
  padding:calc(var(--gap) * 1.1) var(--pad) var(--gap);
  border-top:1px solid var(--line);
  text-align:center;
}
.end-title{
  margin:0;font-family:var(--serif);font-weight:300;
  font-size:var(--fs-ch);letter-spacing:.3em;text-indent:.3em;
}
.end-sub{
  margin:14px 0 0;font-size:var(--fs-body);color:var(--muted);letter-spacing:.08em;
}
.credits{
  max-width:var(--measure);margin:48px auto 0;
  padding-top:32px;border-top:1px solid var(--line);
}
.credits dl{margin:0;display:grid;gap:14px}
.credits div{
  display:grid;grid-template-columns:6.5em 1fr;gap:12px;
  text-align:left;font-size:calc(var(--fs-body) * .92);
}
.credits dt{color:var(--muted);letter-spacing:.16em}
.credits dd{margin:0;color:var(--ink-2)}
.end-line{
  margin:56px auto 0;font-size:var(--fs-small);
  color:var(--ink-2);letter-spacing:.1em;max-width:var(--measure);
}
.end-date{
  margin:8px 0 0;font-size:var(--fs-small);color:var(--muted);letter-spacing:.08em;
}

.foot{
  border-top:1px solid var(--line);
  padding:28px var(--pad) 40px;text-align:center;
}
.foot p{margin:0;font-size:13px;color:var(--muted);letter-spacing:.14em}

/* ---------- 灯箱 ---------- */
.lb{
  position:fixed;inset:0;z-index:80;
  background:rgba(20,18,16,.94);
  display:flex;align-items:center;justify-content:center;
  padding:56px 16px;
}
.lb[hidden]{display:none}
.lb img{
  width:auto;height:auto;
  max-width:calc(100vw - 32px);
  max-height:calc(100vh - 128px);
  object-fit:contain;border-radius:4px;
  box-shadow:0 20px 60px rgba(0,0,0,.5);
}
.lb button{
  position:absolute;border:0;background:transparent;color:#fff;
  cursor:pointer;line-height:1;
  -webkit-appearance:none;appearance:none;
  -webkit-tap-highlight-color:transparent;
}
.lb .lb-close{
  top:10px;right:12px;width:48px;height:48px;padding:0;border-radius:50%;
  background:#fff;color:#1F1E1D;font-size:24px;
  display:grid;place-items:center;
  box-shadow:0 2px 10px rgba(0,0,0,.35);
}
.lb .lb-prev,.lb .lb-next{
  top:50%;transform:translateY(-50%);
  width:48px;height:48px;border-radius:50%;padding:0;
  background:rgba(0,0,0,.55);color:#fff;font-size:26px;
  display:grid;place-items:center;
}
.lb-prev{left:6px}
.lb-next{right:6px}
.lb-prev:hover,.lb-next:hover{opacity:1}
.lb button:focus-visible{outline:2px solid #fff;outline-offset:2px}

/* ---------- 进场（只做首屏，纯 CSS，不依赖 JS 与滚动） ---------- */
@keyframes rise{
  from{opacity:0;transform:translateY(8px)}
  to{opacity:1;transform:none}
}
.cover > *{animation:rise .6s ease-out both}
.cover .eyebrow, .cover h1{animation-delay:0s}
.cover-sub{animation-delay:.08s}
.cover-meta{animation-delay:.16s}

@media (prefers-reduced-motion:reduce){
  .cover > *{animation:none}
  .play{transition:none}
}

/* ---------- 平板/桌面 ---------- */
@media (min-width:760px){
  :root{
    --fs-h1:72px;
    --fs-ch:52px;
    --fs-body:19px;
    --gap:104px;
    --pad:40px;
    --bar:60px;
  }
  html[data-fs="lg"]{--fs-h1:84px;--fs-ch:60px;--fs-body:22px}

  .gallery{
    display:grid;grid-template-columns:repeat(2,1fr);gap:16px;
    margin:36px 0 0;padding:0;overflow:visible;
  }
  .gallery figure{flex:none}
  .gallery img{aspect-ratio:3 / 2}
  .dots{display:none}

  .wall{columns:3;column-gap:14px}
  .wall figure{margin-bottom:14px}

  .lead,.ch-text{text-align:left}
}

@media (min-width:1080px){
  .gallery{grid-template-columns:repeat(3,1fr)}
  .wall{columns:4}
  .cover{padding-top:120px}
}

/* 图少的章节：桌面端不要留空列 */
@media (min-width:760px){
  .gallery[data-count="1"]{max-width:760px;margin-inline:auto}
  .gallery[data-count="2"]{max-width:880px;margin-inline:auto;grid-template-columns:repeat(2,1fr)}
}