:root {
            --bg-color: #f4f7f6;
            --card-bg: #ffffff;
            --text-main: #2d3748;
            --primary: #4a90e2;
            --accent: #2ecc71;
            --text-muted: #718096;
        }

        /* Reset & Base Styles */
        * { box-sizing: border-box; margin: 0; padding: 0; font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; }
        body { background-color: var(--bg-color); color: var(--text-main); padding: 20px; }

        /* Layout */
        .container {
            display: grid;
            grid-template-columns: 250px 1fr;
            gap: 20px;
            max-width: 1400px;
            margin: 0 auto;
        }

        /* Sidebar Navigation */
        aside {
            background: var(--card-bg);
            padding: 20px;
            border-radius: 12px;
            box-shadow: 0 4px 6px rgba(0,0,0,0.05);
            height: fit-content;
        }
        aside h2 { color: var(--primary); margin-bottom: 20px; font-size: 1.5rem; }
        aside ul { list-style: none; }
        aside ul li a {
            display: block;
            padding: 10px 15px;
            color: var(--text-main);
            text-decoration: none;
            border-radius: 8px;
            margin-bottom: 8px;
            transition: all 0.3s;
        }
        aside ul li a:hover, aside ul li a.active {
            background: var(--primary);
            color: white;
            font-weight: bold;
        }

        /* Main Content */
        main { display: flex; flex-direction: column; gap: 20px; }
        
        .welcome-box {
            background: linear-gradient(135deg, var(--primary), #357abd);
            color: white;
            padding: 30px;
            border-radius: 12px;
            box-shadow: 0 4px 15px rgba(74, 144, 226, 0.3);
        }

        /* Grid de Cursuri/Lecții */
        .grid-lessons {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 20px;
        }
        .card {
            background: var(--card-bg);
            padding: 20px;
            border-radius: 12px;
            box-shadow: 0 4px 6px rgba(0,0,0,0.05);
            border-top: 5px solid var(--primary);
            transition: transform 0.2s;
        }
        .card:hover { transform: translateY(-5px); }
        .card h3 { margin-bottom: 10px; color: var(--text-main); }
        .card p { color: var(--text-muted); font-size: 0.95rem; margin-bottom: 15px; line-height: 1.5; }
        
        .btn {
            display: inline-block;
            background: var(--primary);
            color: white;
            padding: 8px 16px;
            border-radius: 6px;
            text-decoration: none;
            font-size: 0.9rem;
            font-weight: 600;
        }
        .btn-success { background: var(--accent); }

        /* Responsive */
        @media (max-width: 768px) {
            .container { grid-template-columns: 1fr; }
            aside { position: sticky; top: 0; z-index: 100; }
        }
                .tabs-navigation { display: flex; gap: 10px; margin-bottom: 20px; margin-top: 10px; }
        .tab-btn {
            padding: 10px 20px; border: none; background: #e2e8f0; color: #4a5568;
            border-radius: 20px; cursor: pointer; font-weight: 600; transition: 0.3s;
        }
        .tab-btn.active, .tab-btn:hover { background: #4a90e2; color: white; }

        .badge { display: inline-block; padding: 4px 8px; font-size: 0.75rem; font-weight: bold; border-radius: 4px; margin-bottom: 10px; }
        .b-9 { background: #e3f2fd; color: #1e88e5; }
        .b-10 { background: #e8f5e9; color: #43a047; }
        @media (max-width: 768px) { .container { grid-template-columns: 1fr; } }
        .b-11 { 
    background: #fff3e0; 
    color: #e65100; /* Portocaliu cald */
}

.b-12 { 
    background: #f3e5f5; 
    color: #4a148c; /* Violet discret */
}

footer{
    display:flex;
    flex-direction:column;
    align-items: center;
}