* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg,#BFF4FF 100%);
    min-height: 100vh;
}

.container.quiz {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.1);
    overflow: hidden;
}

.header {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    color: white;
    padding: 30px;
    text-align: center;
}

.header h1 {
    font-size: 2.5em;
    margin-bottom: 10px;
    font-weight: 700;
}

.header p {
    font-size: 1.2em;
    opacity: 0.9;
}

.progress-bar {
    background: #e0e0e0;
    height: 8px;
    margin: 20px 30px;
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    background: linear-gradient(90deg, #4facfe, #00f2fe);
    height: 100%;
    width: 0%;
    transition: width 0.3s ease;
}

.quiz-container {
    padding: 30px;
}

.question-card {
    background: #f8f9fa;
    border-radius: 15px;
    padding: 25px;
    margin-bottom: 20px;
    border-left: 5px solid #4facfe;
    display: none;
}

.question-card.active {
    display: block;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.question-number {
    color: #4facfe;
    font-weight: bold;
    font-size: 1.1em;
    margin-bottom: 15px;
}

.question-text {
    font-size: 1.3em;
    font-weight: 600;
    color: #333;
    margin-bottom: 20px;
    line-height: 1.4;
}

.options {
    display: grid;
    gap: 12px;
}

.option {
    background: white;
    border: 2px solid #e0e0e0;
    border-radius: 10px;
    padding: 15px 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1.1em;
    display: flex;
    align-items: center;
}

.option:hover {
    border-color: #4facfe;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(79, 172, 254, 0.2);
}

.option.selected {
    border-color: #4facfe;
    background: #f0f8ff;
}

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

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

.option.disabled {
    cursor: not-allowed;
    opacity: 0.7;
}

.option-letter {
    background: #4facfe;
    color: white;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    margin-right: 15px;
    flex-shrink: 0;
}

.correct .option-letter {
    background: #28a745;
}

.incorrect .option-letter {
    background: #dc3545;
}

.feedback {
    margin-top: 15px;
    padding: 15px;
    border-radius: 10px;
    font-weight: 500;
    display: none;
}

.feedback.show {
    display: block;
    animation: fadeIn 0.3s ease;
}

.feedback.correct {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.feedback.incorrect {
    background: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.navigation {
    display: flex;
    justify-content: space-between;
    margin-top: 30px;
    gap: 15px;
}

.nav-btn {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    color: white;
    border: none;
    padding: 12px 25px;
    border-radius: 25px;
    cursor: pointer;
    font-size: 1em;
    font-weight: 600;
    transition: all 0.3s ease;
    min-width: 120px;
}

.nav-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(79, 172, 254, 0.4);
}

.nav-btn:disabled {
    background: #ccc;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.score-display {
    text-align: center;
    font-size: 1.2em;
    color: #666;
    margin-bottom: 20px;
}

.results {
    display: none;
    text-align: center;
    padding: 40px 20px;
}

.results.show {
    display: block;
    animation: slideIn 0.5s ease;
}

.final-score {
    font-size: 3em;
    font-weight: bold;
    color: #4facfe;
    margin-bottom: 20px;
}

.score-message {
    font-size: 1.5em;
    margin-bottom: 30px;
    color: #333;
}

.restart-btn {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 25px;
    cursor: pointer;
    font-size: 1.1em;
    font-weight: 600;
    transition: all 0.3s ease;
}

.restart-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

@media (max-width: 768px) {
    .container {
        margin: 10px;
        border-radius: 15px;
    }
    
    .header h1 {
        font-size: 2em;
    }
    
    .question-text {
        font-size: 1.1em;
    }
    
    .option {
        padding: 12px 15px;
        font-size: 1em;
    }
    
    .navigation {
        flex-direction: column;
    }
}