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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.container {
    max-width: 800px;
    width: 100%;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 30px;
    text-align: center;
}

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

.subtitle {
    font-size: 1.1em;
    opacity: 0.9;
}

.screen {
    padding: 40px;
    animation: fadeIn 0.5s;
}

.hidden {
    display: none;
}

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

.welcome-card {
    text-align: center;
    padding: 40px 20px;
}

.welcome-card h2 {
    color: #667eea;
    font-size: 2em;
    margin-bottom: 20px;
}

.welcome-card p {
    font-size: 1.1em;
    color: #666;
    margin-bottom: 15px;
    line-height: 1.6;
}

.quiz-header {
    margin-bottom: 30px;
}

.progress-bar {
    width: 100%;
    height: 10px;
    background: #e0e0e0;
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 20px;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
    width: 0%;
    transition: width 0.3s ease;
    border-radius: 10px;
}

.quiz-info {
    display: flex;
    justify-content: space-between;
    font-weight: bold;
    color: #667eea;
    font-size: 1.1em;
}

.question-card {
    background: #f8f9fa;
    border-radius: 15px;
    padding: 30px;
    margin-bottom: 30px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

#question-text {
    font-size: 1.5em;
    color: #333;
    margin-bottom: 25px;
    line-height: 1.6;
}

.question-image {
    text-align: center;
    margin: 20px 0;
    font-size: 3em;
}

.options {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.option {
    background: white;
    border: 3px solid #e0e0e0;
    border-radius: 12px;
    padding: 15px 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1.1em;
    display: flex;
    align-items: center;
    gap: 15px;
}

.option:hover {
    border-color: #667eea;
    transform: translateX(5px);
    box-shadow: 0 4px 8px rgba(102, 126, 234, 0.2);
}

.option.selected {
    border-color: #667eea;
    background: #f0f4ff;
}

.option.correct {
    border-color: #4caf50;
    background: #e8f5e9;
}

.option.incorrect {
    border-color: #f44336;
    background: #ffebee;
}

.option.disabled {
    cursor: not-allowed;
    opacity: 0.6;
}

.option-label {
    background: #667eea;
    color: white;
    width: 35px;
    height: 35px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    flex-shrink: 0;
}

.explanation {
    margin-top: 20px;
    padding: 15px;
    border-radius: 10px;
    font-size: 1em;
    line-height: 1.6;
}

.explanation.correct {
    background: #e8f5e9;
    border-left: 4px solid #4caf50;
    color: #2e7d32;
}

.explanation.incorrect {
    background: #fff3e0;
    border-left: 4px solid #ff9800;
    color: #e65100;
}

.quiz-footer {
    display: flex;
    justify-content: center;
    gap: 15px;
}

.btn {
    padding: 15px 30px;
    border: none;
    border-radius: 10px;
    font-size: 1.1em;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: #6c757d;
    color: white;
}

.btn-secondary:hover:not(:disabled) {
    background: #5a6268;
    transform: translateY(-2px);
}

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

.result-card {
    text-align: center;
    padding: 40px 20px;
}

.result-card h2 {
    color: #667eea;
    font-size: 2em;
    margin-bottom: 30px;
}

.score-circle {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    margin: 0 auto 30px;
    box-shadow: 0 10px 30px rgba(102, 126, 234, 0.3);
}

.score-value {
    font-size: 4em;
    font-weight: bold;
    color: white;
}

.score-label {
    font-size: 1.5em;
    color: rgba(255, 255, 255, 0.9);
}

.result-details {
    margin: 30px 0;
    text-align: left;
    max-height: 400px;
    overflow-y: auto;
}

.result-item {
    background: #f8f9fa;
    padding: 15px;
    margin-bottom: 15px;
    border-radius: 10px;
    border-left: 4px solid #667eea;
}

.result-item.correct {
    border-left-color: #4caf50;
}

.result-item.incorrect {
    border-left-color: #f44336;
}

.result-item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
}

.result-item-title {
    font-weight: bold;
    color: #333;
}

.result-item-score {
    font-weight: bold;
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.9em;
}

.result-item-score.correct {
    background: #4caf50;
    color: white;
}

.result-item-score.incorrect {
    background: #f44336;
    color: white;
}

.result-item-explanation {
    color: #666;
    font-size: 0.95em;
    line-height: 1.6;
}

@media (max-width: 600px) {
    header h1 {
        font-size: 1.8em;
    }
    
    #question-text {
        font-size: 1.2em;
    }
    
    .option {
        font-size: 1em;
        padding: 12px 15px;
    }
    
    .btn {
        padding: 12px 20px;
        font-size: 1em;
    }
    
    .score-circle {
        width: 150px;
        height: 150px;
    }
    
    .score-value {
        font-size: 3em;
    }
}