:root{
    --bg:#f7fafb;
    --card:#ffffff;
    --accent:#0f766e;
    --muted:#6b7280;
    --shadow: 0 6px 18px rgba(15,23,42,0.06);
}

*{box-sizing:border-box}
body{
    margin:0;
    font-family: Inter, Arial, Helvetica, sans-serif;
    background:var(--bg);
    color:#0f172a;
}

.app{
    max-width:1100px;
    margin:32px auto;
    display:grid;
    grid-template-columns:1fr 320px;
    gap:22px;
    padding:20px;
}

.app-header{
    grid-column:1 / -1;
    display:flex;
    justify-content:space-between;
    align-items:center;
    gap:16px;
    background:linear-gradient(180deg, rgba(255,255,255,0.9), rgba(255,255,255,0.85));
    padding:18px 22px;
    border-radius:12px;
    box-shadow:var(--shadow);
}

.brand{margin:0;font-size:1.4rem}
.subtitle{margin:4px 0 0;color:var(--muted);font-size:0.9rem}
.user-panel{display:flex;gap:18px;color:var(--muted);font-weight:600}

.main{background:transparent;padding:0}
.section{background:var(--card);padding:20px;border-radius:12px;box-shadow:var(--shadow)}
.section.hidden{display:none}

.section-title{margin:0 0 12px;color:#062a24}

.cards-grid{
    display:grid;
    grid-template-columns:repeat(auto-fit,minmax(220px,1fr));
    gap:14px;
}

.subject-card{
    text-align:left;
    padding:18px;
    border-radius:10px;
    background:linear-gradient(180deg, #ffffff, #fbfdfe);
    border:1px solid #e6eef0;
    cursor:pointer;
    transition:transform .18s ease, box-shadow .18s ease;
}
.subject-card h3{margin:0 0 6px}
.subject-card p{margin:0;color:var(--muted);font-size:0.95rem}
.subject-card:hover{transform:translateY(-6px);box-shadow:0 10px 30px rgba(2,6,23,0.06)}

.menu-row{display:flex;gap:18px;flex-wrap:wrap}
.menu-col{display:flex;flex-direction:column;gap:10px}

.quiz-link{
    padding:12px 14px;border-radius:8px;border:1px solid #e6eef0;background:transparent;
    text-align:left;cursor:pointer;font-weight:600;color:#083b36;
    transition:all .14s ease;
}
.quiz-link:hover{transform:translateY(-4px);box-shadow:var(--shadow)}

.back-link{display:inline-block;margin-bottom:12px;color:var(--muted);text-decoration:none}
.back-link:hover{text-decoration:underline}

.side{display:flex;flex-direction:column;gap:16px}
.card{background:var(--card);padding:14px;border-radius:10px;box-shadow:var(--shadow)}
.ach-list{list-style:none;padding:0;margin:10px 0 0;max-height:220px;overflow:auto}
.ach-list li{padding:8px;border-radius:6px;margin-bottom:6px;background:#fbfdfe;border:1px solid #eef3f4;color:var(--muted);font-size:0.95rem}
.ach-list li.achieved{background:linear-gradient(90deg,#ecfdf5,#ffffff);color:#065f46;font-weight:700}

.small-btn{margin-top:8px;padding:6px 10px;border-radius:8px;border:none;background:#eefaf6;color:#065f46;cursor:pointer}
.small-btn:hover{opacity:.9}

.points-animation{margin-left:8px;color:var(--accent);font-weight:700;opacity:0;transition:opacity .2s ease}

.minimal-leaderboard{width:100%;border-collapse:collapse}
.minimal-leaderboard th, .minimal-leaderboard td{padding:8px;text-align:left;border-bottom:1px solid #f1f5f9}
.minimal-leaderboard th{color:var(--muted);font-size:0.9rem}
.current-user{background:#f1fdfb;font-weight:700}

.quiz-option{
    display:block;width:100%;text-align:left;padding:12px;border-radius:8px;border:1px solid #e6eef0;background:#fff;margin:8px 0;cursor:pointer;
}
.quiz-option.selected{border-color:var(--accent);background:#f0fdfa}
.quiz-nav{display:flex;gap:10px;margin-top:12px}
.extra-btn{padding:8px 12px;border-radius:8px;border:1px solid #e6eef0;background:#fff;cursor:pointer}
.extra-btn:hover{transform:translateY(-3px)}

.theory-card{background:#fff;padding:12px;border-radius:8px;border:1px solid #eef3f4;margin-bottom:10px}
.video-container{margin-top:12px;border-radius:8px;overflow:hidden;border:1px solid #eef3f4}

.flow-block { margin-bottom: 14px; }

.disabled { opacity: 0.55; pointer-events: none; }

.level-up {
    color: #2ecc71;
    font-weight: bold;
    transition: transform 0.3s ease, color 0.3s ease;
    transform: scale(1.0);
}

@media (max-width:980px){
    .app{grid-template-columns:1fr; padding:14px}
    .side{order:2}
}