:root{
  --bg:#0f1724; --panel:#0b1220; --muted:#9aa4b2; --accent:#3ddc97; --glass:rgba(255,255,255,0.04);
  --maxw:1100px;
}
*{box-sizing:border-box}
html,body{height:100%;margin:0;font-family:Inter,ui-sans-serif,system-ui,Segoe UI,Roboto,'Helvetica Neue',Arial;color:#e6eef6;background:linear-gradient(180deg,#071025 0%, #081428 100%);}
.container{max-width:var(--maxw);margin:24px auto;padding:16px;}
.site-header{display:flex;align-items:center;justify-content:space-between;padding:12px 24px;background:transparent;gap:12px;}
.site-header.small{padding:8px 16px;}
.brand{display:flex;align-items:center;gap:12px}
.logo{width:48px;height:48px;background:linear-gradient(90deg,#0ea5a4,#6366f1);border-radius:8px;display:inline-block}
.brand h1{margin:0;font-size:1.2rem}
.subtitle{margin:0;color:var(--muted);font-size:0.8rem}
.nav a{color:var(--muted);text-decoration:none;margin:0 8px;padding:6px 8px;border-radius:8px}
.nav a.active, .nav a:hover{background:var(--glass);color:#fff}
.controls{display:flex;align-items:center;gap:8px}
.controls input{padding:8px;border-radius:8px;border:1px solid rgba(255,255,255,0.04);background:transparent;color:var(--muted)}

.hero{padding:24px;background:linear-gradient(90deg,rgba(255,255,255,0.02),transparent);border-radius:12px}
.hero h2{margin:0 0 8px}
.btn{display:inline-block;padding:10px 14px;border-radius:10px;background:var(--accent);color:#002; text-decoration:none;margin-right:8px}
.btn.secondary{background:transparent;border:1px solid var(--accent);color:var(--accent)}

.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px;margin-top:12px}
.features article{background:var(--panel);padding:16px;border-radius:10px}

.lessons-list .card{background:linear-gradient(180deg,rgba(255,255,255,0.02),transparent);padding:12px;border-radius:10px}
.progress-panel{margin-top:18px;padding:12px;background:var(--panel);border-radius:10px;color:var(--muted)}

.site-footer{max-width:var(--maxw);margin:32px auto;padding:12px;text-align:center;color:var(--muted)}

/* Lesson layout */
.lesson{display:grid;grid-template-columns:1fr 340px;gap:18px;align-items:start}
.lesson-content{background:var(--panel);padding:18px;border-radius:10px}
.lesson-side{position:relative}

.code{width:100%;height:140px;background:#071024;color:#e6eef6;padding:12px;border-radius:8px;border:1px solid rgba(255,255,255,0.03);font-family:monospace;white-space:pre;overflow:auto}
.playframe{width:100%;height:240px;border:1px solid rgba(255,255,255,0.03);border-radius:8px;margin-top:8px;background:#fff}

/* Quiz styling */
.quiz-page{padding:18px}
.quiz-item{background:var(--panel);padding:12px;border-radius:8px;margin-bottom:12px}
.choice{display:block;margin:8px 0;padding:8px;border-radius:8px;border:1px solid rgba(255,255,255,0.03);cursor:pointer}

/* Responsive */
@media (max-width:900px){ .lesson{grid-template-columns:1fr} .controls{display:none} .playframe{height:200px} }

/* Light theme override */
body.theme-light{
  --bg: #f6f9fc; --panel:#ffffff; --muted:#556073; --accent:#0ea5a4; background:linear-gradient(180deg,#f8fafc,#eef2ff);
  color:#0b1220;
}