:root{
  --bg-top:#000000;
  --bg-bottom:#1f2232;
  --gold:#d8b25a;
  --gold-bright:#f0cf86;
  --ink:#e9e6df;
  --bar:rgba(12,13,20,.82);
  --bar-border:rgba(216,178,90,.28);
  --topbar-h:56px;
  --bottombar-h:56px;
}

*{box-sizing:border-box;}
html,body{height:100%;margin:0;}
body{
  font-family:"Trebuchet MS","Segoe UI",system-ui,sans-serif;
  color:var(--ink);
  background:radial-gradient(120% 100% at 50% 0%, #2a2e44 0%, var(--bg-bottom) 45%, var(--bg-top) 100%);
  overflow:hidden;
  -webkit-user-select:none;user-select:none;
  -webkit-tap-highlight-color:transparent;
}

/* ---------- Loader ---------- */
.loader{
  position:fixed;inset:0;z-index:1000;
  display:flex;align-items:center;justify-content:center;
  background:#0b0c12;
  transition:opacity .5s ease;
}
.loader.hidden{opacity:0;pointer-events:none;}
.loader-inner{text-align:center;}
.spinner{
  width:54px;height:54px;margin:0 auto 16px;
  border:3px solid rgba(216,178,90,.2);
  border-top-color:var(--gold);
  border-radius:50%;
  animation:spin 1s linear infinite;
}
@keyframes spin{to{transform:rotate(360deg);}}
.loader-text{color:#cdbb8d;letter-spacing:.18em;font-size:14px;text-transform:uppercase;}

/* ---------- Top bar ---------- */
.topbar{
  position:fixed;top:0;left:0;right:0;height:var(--topbar-h);z-index:60;
  display:flex;align-items:center;justify-content:space-between;
  padding:0 14px;
  background:var(--bar);
  border-bottom:1px solid var(--bar-border);
  backdrop-filter:blur(8px);
}
.brand{display:flex;flex-direction:column;line-height:1;text-decoration:none;}
.brand-mark{
  font-weight:800;letter-spacing:.22em;font-size:18px;
  color:var(--gold-bright);
  text-shadow:0 1px 0 rgba(0,0,0,.6);
}
.brand-sub{margin-top:3px;font-size:11px;letter-spacing:.14em;color:#9a9486;text-transform:uppercase;}
.topbar-actions{display:flex;gap:6px;}

/* ---------- Icon buttons ---------- */
.icon-btn{
  width:40px;height:40px;display:inline-flex;align-items:center;justify-content:center;
  background:transparent;border:1px solid transparent;border-radius:10px;
  color:var(--ink);cursor:pointer;transition:background .15s,border-color .15s,color .15s;
}
.icon-btn:hover{background:rgba(216,178,90,.12);border-color:var(--bar-border);color:var(--gold-bright);}
.icon-btn svg{width:20px;height:20px;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round;}

/* ---------- Stage ---------- */
.stage{
  position:fixed;left:0;right:0;
  top:var(--topbar-h);bottom:var(--bottombar-h);
  display:flex;align-items:center;justify-content:center;
  padding:14px;
}
.book-wrap{
  width:100%;height:100%;
  display:flex;align-items:center;justify-content:center;
}
.flip-book{
  margin:0 auto;
  filter:drop-shadow(0 18px 40px rgba(0,0,0,.6));
}
.flip-book .page{background:#fff;}
.flip-book .page img{width:100%;height:100%;display:block;pointer-events:none;}

/* ---------- Nav arrows ---------- */
.nav-arrow{
  flex:0 0 auto;
  width:48px;height:48px;margin:0 4px;
  display:inline-flex;align-items:center;justify-content:center;
  background:rgba(12,13,20,.55);
  border:1px solid var(--bar-border);border-radius:50%;
  color:var(--gold-bright);cursor:pointer;
  transition:background .15s,transform .15s,opacity .2s;
  z-index:40;
}
.nav-arrow:hover{background:rgba(216,178,90,.18);transform:scale(1.06);}
.nav-arrow svg{width:24px;height:24px;fill:none;stroke:currentColor;stroke-width:2.2;stroke-linecap:round;stroke-linejoin:round;}
.nav-arrow[disabled]{opacity:.25;pointer-events:none;}

/* ---------- Bottom bar ---------- */
.bottombar{
  position:fixed;left:0;right:0;bottom:0;height:var(--bottombar-h);z-index:60;
  display:flex;align-items:center;justify-content:center;gap:12px;
  padding:0 14px;
  background:var(--bar);
  border-top:1px solid var(--bar-border);
  backdrop-filter:blur(8px);
}
.text-btn{
  background:transparent;border:1px solid var(--bar-border);border-radius:8px;
  color:var(--ink);padding:7px 12px;font-size:13px;letter-spacing:.04em;cursor:pointer;
  transition:background .15s,color .15s;
}
.text-btn:hover{background:rgba(216,178,90,.12);color:var(--gold-bright);}
.page-indicator{font-size:13px;color:#cdbb8d;letter-spacing:.08em;min-width:64px;text-align:center;}
.page-range{
  -webkit-appearance:none;appearance:none;
  width:min(36vw,320px);height:4px;border-radius:4px;
  background:linear-gradient(90deg,var(--gold) 0%,var(--gold) var(--fill,0%),rgba(255,255,255,.15) var(--fill,0%));
  outline:none;cursor:pointer;
}
.page-range::-webkit-slider-thumb{-webkit-appearance:none;width:16px;height:16px;border-radius:50%;background:var(--gold-bright);border:2px solid #2a2616;cursor:pointer;}
.page-range::-moz-range-thumb{width:16px;height:16px;border-radius:50%;background:var(--gold-bright);border:2px solid #2a2616;cursor:pointer;}

/* ---------- Thumbnails drawer ---------- */
.scrim{position:fixed;inset:0;z-index:70;background:rgba(0,0,0,.55);opacity:0;pointer-events:none;transition:opacity .25s;}
.scrim.open{opacity:1;pointer-events:auto;}
.thumbs{
  position:fixed;top:0;right:0;bottom:0;z-index:80;width:min(330px,86vw);
  background:#14151f;border-left:1px solid var(--bar-border);
  transform:translateX(100%);transition:transform .3s ease;
  display:flex;flex-direction:column;
}
.thumbs.open{transform:translateX(0);}
.thumbs-head{
  display:flex;align-items:center;justify-content:space-between;
  padding:12px 14px;border-bottom:1px solid var(--bar-border);
  font-size:13px;letter-spacing:.16em;text-transform:uppercase;color:#cdbb8d;
}
.thumbs-grid{
  flex:1;overflow-y:auto;padding:14px;
  display:grid;grid-template-columns:repeat(2,1fr);gap:12px;
}
.thumb{
  position:relative;cursor:pointer;border:2px solid transparent;border-radius:6px;overflow:hidden;
  background:#000;line-height:0;transition:border-color .15s,transform .15s;
}
.thumb img{width:100%;height:auto;display:block;}
.thumb:hover{transform:translateY(-2px);}
.thumb.active{border-color:var(--gold);}
.thumb-num{
  position:absolute;left:0;bottom:0;
  background:rgba(0,0,0,.65);color:#cdbb8d;font-size:11px;
  padding:2px 7px;border-top-right-radius:6px;letter-spacing:.05em;
}

/* ---------- Zoom lightbox ---------- */
.zoom{
  position:fixed;inset:0;z-index:200;background:rgba(6,7,11,.96);
  display:none;
}
.zoom.open{display:block;}
.zoom-scroll{
  position:absolute;inset:0;overflow:auto;
  display:flex;align-items:flex-start;justify-content:center;
  -webkit-overflow-scrolling:touch;
}
.zoom-scroll img{
  display:block;margin:auto;max-width:none;
  width:min(1188px,180vw);height:auto;cursor:zoom-out;
}
.zoom-close{position:fixed;top:12px;right:12px;z-index:210;background:rgba(12,13,20,.7);border-color:var(--bar-border);}

/* ---------- Responsive ---------- */
@media (max-width:640px){
  .brand-mark{font-size:15px;letter-spacing:.16em;}
  .brand-sub{font-size:10px;}
  .nav-arrow{position:fixed;top:50%;transform:translateY(-50%);background:rgba(12,13,20,.35);border:none;}
  .nav-arrow:hover{transform:translateY(-50%) scale(1.06);}
  .nav-prev{left:2px;}
  .nav-next{right:2px;}
  .text-btn{padding:7px 9px;font-size:12px;}
  .page-range{width:34vw;}
  .stage{padding:6px;}
}
@media (max-width:430px){
  .text-btn{display:none;}
  #btn-first,#btn-last{display:inline-block;}
}