body {
    font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont;
    background: #f8fafc;
    color: #0f172a;
}

.card {
    background: #fff;
    border-radius: 12px;
    border: 1px solid #e5e7eb;
    padding: 20px;
}

.badge {
    padding: 4px 10px;
    border-radius: 999px;
    font-size: 12px;
    font-weight: 600;
}

.badge-solved { background:#dcfce7; color:#166534; }
.badge-open   { background:#e0f2fe; color:#075985; }
.badge-locked { background:#fee2e2; color:#991b1b; }

.btn {
    background:#2563eb;
    color:#fff;
    padding:10px 16px;
    border-radius:10px;
    font-weight:600;
}
.btn-outline {
    border:1px solid #cbd5f5;
    color:#1e40af;
    padding:8px 14px;
    border-radius:10px;
}