/* 灯火纪 · 样章翻书组件
   用法：<link rel="stylesheet" href="assets/flip.css">
         <section class="flip" data-book="work"></section>
         <script src="assets/flip.js" defer></script>
   可用 --f-maxh 覆盖书的最大高度（默认 76vh）。 */

.flip{
  --f-paper:#F7F4EE;
  --f-paper-2:#EFEAE1;
  --f-ink:#292723;
  --f-ink-2:#655F57;
  --f-ink-3:#8D857C;
  --f-accent:#984B3D;
  --f-line:#DED7CC;
  --f-serif:"Songti SC","Source Han Serif SC","Noto Serif CJK SC","STSong",serif;
  --f-sans:"PingFang SC","Hiragino Sans GB","Microsoft YaHei",Arial,sans-serif;
  --f-ease:cubic-bezier(.2,.7,.3,1);
  --f-maxh:88vh;
  font-family:var(--f-sans);
  color:var(--f-ink);
  padding:8px 0;
}
.flip *{box-sizing:border-box}
.flip button{font:inherit;cursor:pointer;background:none;border:0;color:inherit}
.flip img{display:block;max-width:100%}

.flip-head{text-align:center;margin-bottom:26px}
.flip-eyebrow{font-size:.76rem;letter-spacing:.22em;color:var(--f-accent);margin:0 0 12px}
.flip-title{font-family:var(--f-serif);font-weight:400;font-size:clamp(1.25rem,2.4vw,1.7rem);letter-spacing:.1em;margin:0}

.flip-stage{display:flex;justify-content:center;padding:0 0 22px;user-select:none;-webkit-user-select:none}
.flip-book{
  position:relative;display:flex;
  aspect-ratio:352 / 246;
  width:min(100%, calc(var(--f-maxh) * 352 / 246));
  border-radius:2px;
  box-shadow:0 1px 3px rgba(41,39,35,.07),0 14px 40px rgba(41,39,35,.11);
  transition:opacity .3s var(--f-ease),transform .3s var(--f-ease);
}
.flip-book.turning{opacity:.25;transform:scale(.988)}
.flip-book::after{
  content:"";position:absolute;left:50%;top:0;bottom:0;width:34px;transform:translateX(-50%);
  pointer-events:none;
  background:linear-gradient(90deg,rgba(41,39,35,0) 0%,rgba(41,39,35,.05) 44%,rgba(41,39,35,.075) 50%,rgba(41,39,35,.05) 56%,rgba(41,39,35,0) 100%);
}
.flip-pg{height:100%;flex:1 1 50%;background:#faf6ee;overflow:hidden;position:relative}
.flip-pg img{width:100%;height:100%;object-fit:cover}
.flip-pg.is-empty{background:var(--f-paper-2);visibility:hidden}

.flip-ctrl{display:flex;align-items:center;justify-content:center;gap:20px}
.flip-ctrl button{
  width:40px;height:40px;border:1px solid var(--f-line);border-radius:50%;
  display:grid;place-items:center;font-size:1rem;
  transition:border-color .25s var(--f-ease),opacity .25s var(--f-ease);
}
.flip-ctrl button:hover:not(:disabled){border-color:var(--f-ink)}
.flip-ctrl button:disabled{opacity:.3;cursor:default}
.flip-count{
  font-size:.84rem;letter-spacing:.12em;color:var(--f-ink-2);
  min-width:84px;text-align:center;font-variant-numeric:tabular-nums;
}
.flip-note{text-align:center;font-size:.75rem;color:var(--f-ink-3);line-height:1.9;margin:14px 0 0}
.flip-hint{display:block;margin-top:2px}

.flip.is-single .flip-book{aspect-ratio:176 / 246;width:min(100%, calc(var(--f-maxh) * 176 / 246))}
.flip.is-single .flip-pg.left{display:none}
.flip.is-single .flip-book::after{display:none}

/* ============ 点击放大（灯箱）============
   书页在跨页布局里只有一半宽度，正文偏小。
   点任意一页可全屏放大查看，点遮罩或按 Esc 关闭。 */
.flip-pg img{cursor:zoom-in}
.flip-pg.is-empty img{cursor:default}

.flip-zoom{
  position:fixed;inset:0;z-index:999;
  display:none;align-items:center;justify-content:center;
  padding:2vh 2vw;
  background:rgba(41,39,35,.94);
  cursor:zoom-out;
}
.flip-zoom.on{display:flex}
.flip-zoom img{
  width:auto;height:auto;
  max-width:96vw;max-height:96vh;
  border-radius:2px;
  box-shadow:0 24px 70px rgba(0,0,0,.55);
}
.flip-zoom-close{
  position:absolute;top:18px;right:22px;
  width:42px;height:42px;border-radius:50%;
  display:grid;place-items:center;
  font-size:1.15rem;line-height:1;color:#fff;
  background:rgba(255,255,255,.07);
  border:1px solid rgba(255,255,255,.34);
  transition:border-color .25s var(--f-ease),background .25s var(--f-ease);
}
.flip-zoom-close:hover{border-color:#fff;background:rgba(255,255,255,.14)}

@media (prefers-reduced-motion: reduce){
  .flip-book{transition-duration:.01ms}
}