@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;600;700&display=swap');
:root{--blue:#063970;--yellow:#ffd54a;--muted:#6b7280;--card:#ffffffcc}
*{box-sizing:border-box;margin:0;padding:0;font-family:Inter,system-ui,Arial}
body{background:#f6fbff;color:#063970;min-height:100vh}
.container{max-width:1200px;margin:24px auto;padding:18px}
.header{display:flex;justify-content:space-between;align-items:center;gap:12px}
.brand{display:flex;align-items:center;gap:12px}
.logo{width:64px;height:64px;border-radius:12px;background:var(--blue);display:flex;align-items:center;justify-content:center;color:var(--yellow);font-weight:800;font-size:20px}
h1{font-size:1.4rem;color:var(--blue)}
.sub{color:var(--muted)}
.nav a{margin-left:12px;text-decoration:none;color:var(--blue);font-weight:600}
.hero{display:flex;gap:20px;background:linear-gradient(90deg,#e6f3ff,white);padding:20px;border-radius:12px;align-items:center}
.hero img{width:420px;border-radius:8px}
.card{background:var(--card);padding:14px;border-radius:10px;box-shadow:0 6px 18px rgba(3,57,100,0.06);border:1px solid rgba(3,57,100,0.04)}
.input, select{width:100%;padding:10px;border-radius:8px;border:1px solid #e6f3ff;margin-top:8px}
.btn{padding:10px 14px;border-radius:8px;border:none;cursor:pointer;font-weight:700}
.btn-primary{background:var(--yellow);color:var(--blue);box-shadow:0 6px 18px rgba(3,57,100,0.06)}
.subject-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:14px;margin-top:16px}
.subject-card{background:white;padding:12px;border-radius:10px;cursor:pointer;transition:transform .15s ease,box-shadow .15s ease;border:1px solid #f0f8ff}
.subject-card:hover{transform:translateY(-6px);box-shadow:0 12px 30px rgba(3,57,100,0.08)}
.chapter-list, .topic-list{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin-top:12px}
.chapter-card, .topic-card{background:#fff;padding:10px;border-radius:8px;cursor:pointer;border:1px solid #f0f8ff}
.video-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-top:12px}
.video-embed iframe{width:100%;height:200px;border-radius:8px;border:0}
.footer{margin-top:18px;color:var(--muted);text-align:center;font-size:0.9rem}
@media(max-width:1000px){.subject-grid{grid-template-columns:repeat(2,1fr)}.chapter-list,.topic-list,.video-grid{grid-template-columns:repeat(1,1fr)}.hero{flex-direction:column}.hero img{width:100%}}