:root{--bg1:#e7f5ec;--bg2:#9dd0b3;--bg3:#2c6f53;--ink:#123a2a}
*{box-sizing:border-box}
body{margin:0;font-family:"PingFang SC","Noto Sans SC",system-ui,sans-serif;background:
  radial-gradient(circle at 15% 10%, #f3fff8 0, transparent 35%),
  radial-gradient(circle at 85% 90%, #75b594 0, transparent 30%),
  linear-gradient(145deg,var(--bg1),var(--bg2) 45%,var(--bg3));
  min-height:100vh;color:var(--ink)}
.topbar{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:12px 16px;background:rgba(235,252,243,.72);backdrop-filter:blur(8px);border-bottom:1px solid #afd7c0;position:sticky;top:0;z-index:5}
.topbar h1{margin:0;font-size:18px}.back{text-decoration:none;color:#1e6549;font-weight:700}
.book-wrap{display:grid;grid-template-columns:100px minmax(280px,900px) 100px;gap:8px;align-items:center;justify-content:center;padding:24px 10px}
.nav{height:44px;border:none;border-radius:12px;background:linear-gradient(135deg,#3d8d68,#215c43);color:#ecfff5;font-weight:700;cursor:pointer}
.nav:disabled{opacity:.45;cursor:not-allowed}
.book{height:78vh;max-height:920px;min-height:420px;position:relative;perspective:2200px}
.page{position:absolute;inset:0;transform-origin:left center;transition:transform .8s ease, box-shadow .6s ease;border-radius:8px;overflow:hidden;background:#f1f6f3;box-shadow:0 14px 30px rgba(0,0,0,.22);display:flex;align-items:center;justify-content:center;padding:8px;backface-visibility:hidden}
.page canvas{width:100%;height:100%;display:block;border-radius:4px;background:#fff;object-fit:contain}
.page.zoom-page canvas{transform:scale(1.22);transform-origin:center center}
.page.flipped{transform:rotateY(-180deg);box-shadow:0 8px 14px rgba(0,0,0,.15)}

/* 第一页：直接使用PDF第一页，完整显示，不裁切，不显示白色外底 */
.page.first-pdf-cover{background:#2c6f53;padding:0}
.page.first-pdf-cover canvas{width:auto;height:100%;max-width:100%;object-fit:contain;background:transparent;border-radius:0}

.footer{text-align:center;padding:6px 10px 18px;color:#104131;font-size:13px}
@media (max-width:900px){
  .book-wrap{grid-template-columns:70px minmax(240px,1fr) 70px}
  .topbar h1{font-size:14px}
}