/* Reset and base styles */
* {
    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: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

/* Header styles */
header h1 {
    text-align: center;
    color: white;
    font-size: 2.5rem;
    margin-bottom: 2rem;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

/* Screen management - only show active screen */
.screen {
    display: none;
    background: white;
    border-radius: 15px;
    padding: 2rem;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
    animation: fadeIn 0.5s ease-in;
}

.screen.active {
    display: block;
}

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

/* Start screen styles */
#start-screen {
    text-align: center;
}

#start-screen h2 {
    color: #4a5568;
    margin-bottom: 1rem;
    font-size: 2rem;
}

#start-screen p {
    color: #718096;
    font-size: 1.1rem;
    margin-bottom: 2rem;
}

/* Quiz header with progress and score */
.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid #e2e8f0;
}

.progress-info, .score-info {
    font-weight: bold;
    color: #4a5568;
    font-size: 1.1rem;
}

/* Question container */
.question-container h2 {
    color: #2d3748;
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
    line-height: 1.4;
}

/* Answer options styling */
.options-container {
    margin-bottom: 2rem;
}

.option {
    display: block;
    margin-bottom: 1rem;
    padding: 1rem;
    background: #f7fafc;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
}

.option:hover {
    background: #edf2f7;
    border-color: #cbd5e0;
    transform: translateX(5px);
}

.option:focus-within {
    outline: 3px solid #667eea;
    outline-offset: 2px;
}

/* Hide default radio button but keep it functional */
.option input[type="radio"] {
    opacity: 0;
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    margin: 0;
    cursor: pointer;
}

.option label {
    cursor: pointer;
    display: block;
    font-weight: 500;
    color: #4a5568;
}

/* Selected option styling */
.option.selected {
    background: #667eea;
    border-color: #5a67d8;
    color: white;
}

.option.selected label {
    color: white;
}

/* Feedback styling */
.feedback {
    text-align: center;
    padding: 1.5rem;
    border-radius: 10px;
    margin-top: 1rem;
}

.feedback.correct {
    background: #c6f6d5;
    border: 2px solid #68d391;
    color: #22543d;
}

.feedback.incorrect {
    background: #fed7d7;
    border: 2px solid #fc8181;
    color: #742a2a;
}

.feedback.hidden {
    display: none;
}

#feedback-text {
    font-weight: bold;
    margin-bottom: 1rem;
}

/* Results screen */
#results-screen {
    text-align: center;
}

#results-screen h2 {
    color: #4a5568;
    margin-bottom: 2rem;
    font-size: 2rem;
}

.score-display {
    font-size: 4rem;
    font-weight: bold;
    color: #667eea;
    margin-bottom: 1rem;
}

#score-message {
    font-size: 1.2rem;
    color: #718096;
    margin-bottom: 2rem;
}

/* Button styles */
.btn {
    padding: 12px 30px;
    font-size: 1.1rem;
    font-weight: bold;
    border: none;
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.btn:focus {
    outline: 3px solid rgba(102, 126, 234, 0.5);
    outline-offset: 2px;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.6);
}

.btn-primary:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
    box-shadow: 0 2px 8px rgba(102, 126, 234, 0.2);
}

.btn-secondary {
    background: #4a5568;
    color: white;
}

.btn-secondary:hover {
    background: #2d3748;
    transform: translateY(-2px);
}

/* Responsive design */
@media (max-width: 600px) {
    .container {
        padding: 10px;
    }
    
    header h1 {
        font-size: 2rem;
        margin-bottom: 1rem;
    }
    
    .screen {
        padding: 1.5rem;
    }
    
    .quiz-header {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .question-container h2 {
        font-size: 1.3rem;
    }
    
    .score-display {
        font-size: 3rem;
    }
}