:root{
  --bg:#f7f8fb;
  --card:#ffffff;
  --accent:#1a73e8;
  --muted:#666;
  --max-width:1200px;
}
*{box-sizing:border-box}
body{font-family:Inter,Segoe UI,Arial,sans-serif;background:var(--bg);margin:0;color:#222}
.site-header{display:flex;align-items:center;justify-content:space-between;padding:16px 20px;background:#fff;border-bottom:1px solid #eee;position:relative;max-width:var(--max-width);margin:0 auto}
.brand{font-weight:700;font-size:1.1rem}
.main-nav{margin-left:auto}
.main-nav ul{display:flex;gap:8px;margin:0;padding:0;list-style:none}
.main-nav .nav-btn{background:transparent;border:0;padding:8px 12px;border-radius:6px;cursor:pointer}
.main-nav .nav-btn.active{background:var(--accent);color:#fff}
.top-controls{display:flex;gap:12px;align-items:center;padding:12px 20px;max-width:var(--max-width);margin:0 auto}
.levels{display:flex;gap:8px;flex-wrap:wrap}
.level-btn{background:#fff;border:1px solid #e6e6e6;padding:6px 10px;border-radius:6px;cursor:pointer}
.level-btn.active{background:var(--accent);color:#fff;border-color:var(--accent)}
.search input{padding:8px 10px;border-radius:8px;border:1px solid #ddd;width:220px}
.content{padding:20px;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px;max-width:var(--max-width);margin:0 auto}
@media (max-width:1100px){
  .content{grid-template-columns:repeat(2,minmax(0,1fr));}
}
@media (max-width:680px){
  .content{grid-template-columns:1fr}
}
.card{background:var(--card);border:1px solid #eee;padding:12px;border-radius:8px;display:flex;flex-direction:column;gap:10px}
.card h3{margin:0;font-size:1rem}
.meta{color:var(--muted);font-size:0.9rem}
.video-wrap{position:relative;padding-top:56.25%;overflow:hidden;border-radius:6px}
.video-wrap iframe{position:absolute;left:0;top:0;width:100%;height:100%;border:0}
.pdf-preview{height:220px;border-radius:6px;border:1px solid #ddd}
.actions{display:flex;gap:8px;justify-content:center}
.btn{padding:6px 8px;border-radius:6px;border:1px solid #ddd;background:#fff;cursor:pointer;text-decoration:none;display:inline-block}
.btn, .btn:link, .btn:visited { text-decoration: none; }
.btn.primary{background:var(--accent);color:#fff;border-color:var(--accent)}
/* YouTube button specific style */
.youtube-btn{background:#1e88ff;color:#fff;border-color:#1669c7}
.site-footer{text-align:center;padding:16px;color:#888;font-size:0.9rem}

@media (max-width:520px){
  .search input{width:140px}
  .main-nav ul{gap:4px}
}
/* Admin panel styles */

/* Login page — scoped, simple centered layout for index.php */
body.login-page{display:flex;align-items:center;justify-content:center;min-height:100vh;padding:20px;background:var(--bg)}
body.login-page > div{width:100%;max-width:440px;background:var(--card);border:1px solid #eee;padding:20px;border-radius:12px;box-shadow:0 8px 24px rgba(16,24,40,0.06);text-align:center}
body.login-page h3{margin:0 0 12px;font-size:1.05rem;color:#111}
.login-section{margin-top:12px;display:flex;justify-content:center}