:root{
  --bg:#f4efe6;
  --ink:#2b2620;
  --muted:#8a8175;
  --accent:#8a6d3b;
  --gold:#b8924a;
  --bar:#1f1b17;
  --bar-ink:#efe7d8;
  --card:#fffdf8;
  --shadow:0 10px 30px rgba(0,0,0,.18);
  --reader-bg:#efe7d6;
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
html,body{margin:0;height:100%}
body{
  font-family:"Noto Serif TC","Songti TC","STSong","SimSun","Microsoft JhengHei",serif;
  background:var(--bg);color:var(--ink);
  -webkit-font-smoothing:antialiased;overflow:hidden;
}
.hidden{display:none !important}
.screen{position:fixed;inset:0;display:flex;flex-direction:column}
button{font-family:inherit;cursor:pointer}
svg{width:22px;height:22px;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round}

/* ============ LIBRARY ============ */
#library{
  background:
    radial-gradient(120% 80% at 50% -10%, #2a2018 0%, #1a140f 60%, #120d0a 100%);
  color:#efe3cf;overflow:auto;display:block;
}
.lib-head{padding:28px 22px 10px;max-width:1100px;margin:0 auto;display:flex;align-items:center;justify-content:space-between;gap:16px}
.lib-brand{display:flex;align-items:center;gap:16px}
.lib-logo{width:54px;height:54px;border-radius:12px;box-shadow:var(--shadow)}
.lib-brand h1{margin:0;font-size:26px;letter-spacing:3px;color:#f3e6c9}
.lib-brand p{margin:2px 0 0;color:#bda77e;letter-spacing:6px;font-size:12px}
.lib-body{max-width:1100px;margin:0 auto;padding:18px 22px 60px;width:100%}

/* language toggle */
.lang-toggle{display:inline-flex;border:1px solid rgba(184,146,74,.5);border-radius:20px;overflow:hidden;flex:0 0 auto}
.lang-toggle button{background:transparent;border:0;color:#caa763;padding:6px 14px;font-size:13px;letter-spacing:1px;font-family:inherit}
.lang-toggle button.active{background:linear-gradient(180deg,#d8b771,#bd9748);color:#1a140f;font-weight:700}
.lang-toggle.compact{border-color:rgba(255,255,255,.25)}
.lang-toggle.compact button{color:var(--bar-ink);padding:5px 10px;font-size:12px}
.lang-toggle.compact button.active{color:#1a140f}
.lib-section-title{
  font-size:15px;letter-spacing:8px;color:#caa763;margin:18px 0 18px;
  border-bottom:1px solid rgba(184,146,74,.3);padding-bottom:12px;font-weight:600;
}
.shelf{display:grid;grid-template-columns:repeat(auto-fill,minmax(180px,1fr));gap:30px 26px}
.book-card{
  display:flex;flex-direction:column;align-items:center;gap:12px;text-align:center;color:inherit;
}
.cover-btn{background:transparent;border:0;padding:0;width:100%;cursor:pointer;transition:transform .18s ease}
.cover-btn:hover{transform:translateY(-6px)}
.book-cover{
  width:100%;aspect-ratio:2/3;border-radius:4px 8px 8px 4px;object-fit:cover;display:block;
  box-shadow:var(--shadow), -6px 0 0 -2px rgba(0,0,0,.25);
  background:#3a2c20;border:1px solid rgba(184,146,74,.25);
}
.book-meta{line-height:1.5;width:100%}
.book-meta .bt{font-size:16px;color:#f1e4c6;letter-spacing:1px;min-height:2.6em;display:flex;align-items:center;justify-content:center}
.edition-chips{display:flex;flex-wrap:wrap;gap:6px;justify-content:center;margin-top:8px}
.chip{
  position:relative;background:rgba(184,146,74,.14);border:1px solid rgba(184,146,74,.4);
  color:#e3cfa0;border-radius:16px;padding:4px 12px;font-size:12px;letter-spacing:1px;font-family:inherit;
  transition:background .15s, transform .1s;
}
.chip:hover{background:linear-gradient(180deg,#d8b771,#bd9748);color:#1a140f;border-color:transparent}
.chip:active{transform:scale(.94)}
.chip-dot{display:inline-block;width:6px;height:6px;border-radius:50%;background:#7fbf7f;margin-left:6px;vertical-align:middle}
.lib-empty{text-align:center;color:#a8916a;font-size:15px;letter-spacing:2px;padding:60px 20px}
.lib-foot{text-align:center;color:#6f5f48;font-size:12px;letter-spacing:3px;margin-top:48px}

/* ============ READER ============ */
#reader{background:var(--reader-bg)}
.bar{
  position:absolute;left:0;right:0;z-index:30;background:var(--bar);color:var(--bar-ink);
  display:flex;align-items:center;gap:8px;padding:10px 12px;
  transition:transform .25s ease, opacity .25s ease;
}
.topbar{top:0;padding-top:max(10px,env(safe-area-inset-top))}
.bottombar{bottom:0;padding-bottom:max(10px,env(safe-area-inset-bottom))}
#reader.immersive .bar{transform:translateY(var(--hide,0));opacity:0;pointer-events:none}
#reader.immersive .topbar{--hide:-110%}
#reader.immersive .bottombar{--hide:110%}
.topbar-title{flex:1;text-align:center;font-size:15px;letter-spacing:2px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.topbar-actions{display:flex;gap:2px;align-items:center}
.panel-list .sub{color:var(--muted);font-size:13px}
.icon-btn{
  background:transparent;border:0;color:inherit;width:40px;height:40px;border-radius:10px;
  display:inline-flex;align-items:center;justify-content:center;font-size:18px;
}
.icon-btn:hover{background:rgba(255,255,255,.1)}
.icon-btn:active{transform:scale(.92)}

/* Stage */
.stage{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;overflow:hidden}
.page-wrap{
  position:relative;height:100%;width:100%;display:flex;align-items:center;justify-content:center;
  padding:8px;
}
.page-img{
  max-width:100%;max-height:100%;object-fit:contain;user-select:none;
  box-shadow:0 6px 26px rgba(0,0,0,.28);background:#fff;border-radius:2px;
  transition:opacity .12s ease;
}
.page-img.preload{display:none}

/* Tap zones */
.nav-zone{position:absolute;top:0;bottom:0;z-index:20;background:transparent;border:0;padding:0}
.nav-prev{left:0;width:32%}
.nav-next{right:0;width:32%}
.nav-center{left:32%;width:36%}

/* edge arrows (desktop hint) */
/* desktop-only hover hint arrows; hidden on touch devices */
.edge-arrow{display:none}
@media (hover:hover) and (pointer:fine){
  .edge-arrow{
    position:absolute;top:50%;transform:translateY(-50%);z-index:21;
    width:44px;height:64px;display:flex;align-items:center;justify-content:center;
    color:#5b5246;background:rgba(255,255,255,.55);border-radius:10px;opacity:0;
    transition:opacity .2s;pointer-events:none;backdrop-filter:blur(2px);
  }
  .edge-arrow svg{width:28px;height:28px;stroke-width:2.4}
  .edge-left{left:10px}.edge-right{right:10px}
  .stage:hover .edge-arrow{opacity:.85}
}

/* bookmark flag on page */
.bookmark-flag{
  position:absolute;top:62px;right:16px;z-index:25;width:40px;height:48px;border:0;
  background:rgba(255,255,255,.42);border-radius:0 0 8px 8px;backdrop-filter:blur(2px);
  color:rgba(110,100,85,.7);transition:color .2s, transform .15s, top .25s ease;
  display:flex;align-items:flex-start;justify-content:center;padding-top:2px;
}
.bookmark-flag svg{width:26px;height:34px;stroke-width:1.6}
#reader.immersive .bookmark-flag{top:max(8px,env(safe-area-inset-top));background:rgba(255,255,255,.3)}
.bookmark-flag.active{color:var(--gold)}
.bookmark-flag.active svg{fill:var(--gold)}
.bookmark-flag:active{transform:scale(.85)}

/* bottom bar controls */
.slider{
  flex:1;-webkit-appearance:none;appearance:none;height:4px;border-radius:4px;
  background:rgba(255,255,255,.25);outline:none;
}
.slider::-webkit-slider-thumb{-webkit-appearance:none;width:18px;height:18px;border-radius:50%;background:var(--gold);box-shadow:0 1px 4px rgba(0,0,0,.4)}
.slider::-moz-range-thumb{width:18px;height:18px;border:0;border-radius:50%;background:var(--gold)}
.page-indicator{min-width:74px;text-align:center;font-size:13px;letter-spacing:1px;font-variant-numeric:tabular-nums}

/* ============ Panels (TOC / Bookmarks) ============ */
.panel{
  position:absolute;top:0;bottom:0;right:0;z-index:50;width:min(360px,86vw);
  background:var(--card);color:var(--ink);box-shadow:-12px 0 40px rgba(0,0,0,.3);
  display:flex;flex-direction:column;transform:translateX(0);transition:transform .26s ease;
}
.panel.hidden{transform:translateX(105%);display:flex !important}
.panel-head{
  display:flex;align-items:center;justify-content:space-between;padding:16px 18px;
  border-bottom:1px solid #e7ddc9;font-size:17px;letter-spacing:3px;color:var(--accent);
  background:linear-gradient(180deg,#fbf6ec,#fff);
}
.panel-head .icon-btn{color:var(--muted)}
.panel-list{list-style:none;margin:0;padding:8px 0;overflow:auto;flex:1}
.panel-list li{padding:0}
.panel-list button.row{
  width:100%;text-align:left;background:transparent;border:0;padding:14px 20px;color:var(--ink);
  display:flex;justify-content:space-between;align-items:center;gap:10px;font-size:15px;letter-spacing:1px;
  border-bottom:1px solid #f0e9da;
}
.panel-list button.row:hover{background:#f7f1e3}
.panel-list .row .pg{color:var(--muted);font-size:12px;font-variant-numeric:tabular-nums;white-space:nowrap}
.panel-list .row.current{color:var(--accent);font-weight:700;background:#f6efdd}
.panel-list .row .del{color:#b86b5a;padding:4px 8px;border-radius:8px;font-size:13px}
.panel-list .row .del:hover{background:#f3dcd6}
.panel-empty{padding:30px 24px;color:var(--muted);font-size:14px;line-height:1.9;text-align:center}

.scrim{position:absolute;inset:0;z-index:40;background:rgba(0,0,0,.35);transition:opacity .2s}

/* theme variants for reader background */
#reader.bg-sepia{--reader-bg:#efe7d6}
#reader.bg-light{--reader-bg:#fbfbf9}
#reader.bg-dark{--reader-bg:#181410}
#reader.bg-dark .page-img{box-shadow:0 6px 26px rgba(0,0,0,.6)}

@media (max-width:520px){
  .lib-brand h1{font-size:22px}
  .shelf{grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:20px}
  .topbar-title{font-size:14px}
}