:root{
  --blue-900:#0A2E45;
  --blue-700:#0E4D73;
  --blue-600:#1596D9;
  --blue-500:#2CABE3;
  --blue-050:#F1FAFF;
  --line:#CFE7F3;
  --white:#FFFFFF;
  --ink:#0C2233;
  --ink-soft:#3E5A6C;
  --font-display:'Unbounded',sans-serif;
  --font-body:'Inter',sans-serif;
}
*{box-sizing:border-box}
html,body{margin:0;min-height:100%;font-family:var(--font-body);color:var(--ink);background:#f5faff}
body{padding:20px}
.viewer-shell{max-width:1280px;margin:0 auto;background:var(--white);border:1px solid var(--line);border-radius:22px;box-shadow:0 20px 60px rgba(10,46,69,.10);overflow:hidden}
.viewer-head{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:18px 22px;border-bottom:1px solid var(--line);flex-wrap:wrap}
.viewer-title{font-family:var(--font-display);font-size:18px;font-weight:700;color:var(--blue-900);line-height:1.25;word-break:break-word}
.viewer-actions{display:flex;gap:10px;flex-wrap:wrap}
.btn{display:inline-flex;align-items:center;justify-content:center;padding:11px 16px;border-radius:11px;text-decoration:none;font-weight:600;font-size:14px}
.btn-primary{background:var(--blue-600);color:#fff}
.btn-light{background:var(--blue-050);color:var(--blue-700);border:1px solid var(--line)}
.viewer-body{padding:12px;background:#edf5f9}
.viewer-frame{display:block;width:100%;height:calc(100vh - 120px);min-height:620px;border:0;border-radius:14px;background:#fff}
.viewer-fallback{padding:18px;text-align:center;color:var(--ink-soft);font-size:14px}
@media (max-width:700px){
  body{padding:8px}
  .viewer-shell{border-radius:16px}
  .viewer-head{padding:14px}
  .viewer-title{font-size:15px}
  .viewer-frame{height:calc(100vh - 145px);min-height:520px}
}