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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f9f9f9;
}

header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-align: center;
    padding: 2rem 1rem;
    position: relative;
}

.built-with {
    position: absolute;
    top: 1rem;
    left: 1rem;
    color: rgba(255,255,255,0.9);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: color 0.3s;
}

.built-with:hover {
    color: white;
}

header h1 {
    font-size: 2.2rem;
    margin-bottom: 0.5rem;
}

header p {
    font-size: 1.1rem;
    opacity: 0.9;
}

main {
    max-width: 900px;
    margin: 2rem auto;
    padding: 0 1rem;
}

#quiz-container, #results {
    background: white;
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 8px 24px rgba(0,0,0,0.1);
}

h2 {
    color: #2c3e50;
    margin-bottom: 1.5rem;
    border-bottom: 2px solid #ecf0f1;
    padding-bottom: 0.5rem;
}

.question {
    margin-bottom: 2rem;
    padding: 1.5rem;
    background-color: #f8f9fa;
    border-radius: 10px;
    border-left: 4px solid #3498db;
}

.question h3 {
    margin-bottom: 1rem;
    color: #2c3e50;
}

.options {
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
}

.option {
    padding: 1rem;
    background-color: white;
    border: 1px solid #ddd;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
}

.option:hover {
    background-color: #f0f7ff;
    border-color: #3498db;
    transform: translateX(4px);
}

.option input[type="radio"] {
    margin-right: 1rem;
    accent-color: #3498db;
}

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

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

#controls {
    display: flex;
    justify-content: space-between;
    margin-top: 2rem;
}

button {
    padding: 0.8rem 1.5rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    transition: background-color 0.3s;
}

#prev-btn, #next-btn {
    background-color: #3498db;
    color: white;
}

#prev-btn:hover, #next-btn:hover {
    background-color: #2980b9;
}

#submit-btn {
    background-color: #2ecc71;
    color: white;
    margin-left: auto;
}

#submit-btn:hover {
    background-color: #27ae60;
}

#results {
    text-align: center;
}

#score-display {
    font-size: 1.5rem;
    font-weight: bold;
    color: #2c3e50;
    margin: 1.5rem 0;
}

#feedback {
    text-align: left;
    margin: 2rem 0;
    padding: 1.5rem;
    background-color: #f8f9fa;
    border-radius: 10px;
    border-left: 4px solid #e74c3c;
}

#feedback p {
    margin-bottom: 0.8rem;
}

#restart-btn {
    background-color: #9b59b6;
    color: white;
    padding: 0.8rem 2rem;
    font-size: 1rem;
}

#restart-btn:hover {
    background-color: #8e44ad;
}

footer {
    text-align: center;
    padding: 2rem 1rem;
    margin-top: 3rem;
    color: #7f8c8d;
    font-size: 0.9rem;
}

footer a {
    color: #3498db;
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

@media (max-width: 768px) {
    header h1 {
        font-size: 1.8rem;
    }
    
    header p {
        font-size: 1rem;
    }
    
    main {
        margin: 1rem auto;
        padding: 0;
    }
    
    #quiz-container, #results {
        padding: 1.5rem;
    }
    
    .question {
        padding: 1rem;
    }
    
    button {
        padding: 0.7rem 1.2rem;
        font-size: 0.9rem;
    }
    
    #controls {
        flex-direction: column;
        gap: 1rem;
    }
    
    #controls button {
        width: 100%;
    }
}