* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', 'SolaimanLipi', sans-serif;
}

body {
    display: flex;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}

.sidebar {
    width: 280px;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    color: white;
    height: 100vh;
    position: fixed;
    padding: 30px 20px;
    border-right: 1px solid rgba(255,255,255,0.1);
}

.logo h2 {
    font-size: 24px;
    margin-bottom: 40px;
    text-align: center;
}

.sidebar nav a {
    display: block;
    color: white;
    text-decoration: none;
    padding: 15px 20px;
    margin: 10px 0;
    border-radius: 10px;
    transition: 0.3s;
}

.sidebar nav a:hover,
.sidebar nav a.active {
    background: rgba(255, 255, 255, 0.2);
    transform: translateX(5px);
}

.sidebar nav a i {
    margin-right: 15px;
    width: 20px;
    text-align: center;
}

.main-content {
    margin-left: 280px;
    padding: 30px;
    width: calc(100% - 280px);
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 40px;
    color: white;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 15px;
    background: rgba(255,255,255,0.1);
    padding: 10px 20px;
    border-radius: 50px;
}

.hero-section {
    text-align: center;
    padding: 60px 20px;
    color: white;
    background: rgba(255,255,255,0.1);
    border-radius: 20px;
    margin-bottom: 40px;
    backdrop-filter: blur(10px);
}

.hero-section h1 {
    font-size: 48px;
    margin-bottom: 30px;
}

.hero-buttons {
    display: flex;
    gap: 20px;
    justify-content: center;
}

.btn {
    padding: 15px 40px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: bold;
    transition: 0.3s;
}

.btn-primary {
    background: white;
    color: #667eea;
}

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid white;
}

.btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 50px;
}

.feature-card, .stat-card, .subject-card {
    background: white;
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    text-align: center;
    transition: 0.3s;
}

.feature-card:hover, .subject-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 40px rgba(0,0,0,0.2);
}

.feature-card i, .stat-card i {
    font-size: 48px;
    color: #667eea;
    margin-bottom: 20px;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 25px;
    margin-bottom: 40px;
}

.stat-card p {
    font-size: 36px;
    font-weight: bold;
    color: #333;
    margin-top: 10px;
}

.section {
    margin-bottom: 50px;
}

.section h2 {
    color: white;
    margin-bottom: 25px;
    font-size: 28px;
}

.subject-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 25px;
}

.subject-card {
    cursor: pointer;
}

.subject-card h3 {
    color: #333;
    margin-bottom: 10px;
    font-size: 20px;
}

.quiz-container {
    background: white;
    padding: 40px;
    border-radius: 20px;
    max-width: 800px;
    margin: 0 auto;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 2px solid #eee;
}

.timer {
    font-size: 24px;
    font-weight: bold;
    color: #e74c3c;
}

.score {
    font-size: 24px;
    font-weight: bold;
    color: #27ae60;
}

.question h3 {
    font-size: 22px;
    margin-bottom: 30px;
    color: #333;
}

.options {
    display: grid;
    gap: 15px;
}

.option {
    padding: 18px 25px;
    background: #f8f9fa;
    border: 2px solid #dee2e6;
    border-radius: 12px;
    cursor: pointer;
    transition: 0.3s;
    font-size: 18px;
}

.option:hover {
    background: #e9ecef;
    border-color: #667eea;
}

.option.correct {
    background: #d4edda;
    border-color: #28a745;
    color: #155724;
}

.option.wrong {
    background: #f8d7da;
    border-color: #dc3545;
    color: #721c24;
}

.question-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 30px;
}

.nav-btn {
    padding: 12px 30px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    font-weight: bold;
    transition: 0.3s;
}

.nav-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

@media (max-width: 768px) {
    body {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
    }
    
    .main-content {
        margin-left: 0;
        width: 100%;
    }
    
    .hero-section h1 {
        font-size: 32px;
    }
}