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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f8f9fa;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem;
}

.screen {
    display: none;
    background: white;
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.screen.active {
    display: block;
}

h1 {
    text-align: center;
    margin-bottom: 2rem;
    color: #2c3e50;
}

h2 {
    margin-bottom: 1.5rem;
    color: #34495e;
}

.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: #495057;
}

input[type="text"],
input[type="email"] {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid #e9ecef;
    border-radius: 4px;
    font-size: 1rem;
    transition: border-color 0.2s;
}

input[type="text"]:focus,
input[type="email"]:focus {
    outline: none;
    border-color: #007bff;
}

.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    text-decoration: none;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-primary {
    background-color: #007bff;
    color: white;
}

.btn-primary:hover {
    background-color: #0056b3;
}

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

.btn-secondary:hover {
    background-color: #545b62;
}

.btn-warning {
    background-color: #ffc107;
    color: #212529;
}

.btn-warning:hover {
    background-color: #e0a800;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    background-color: #6c757d !important;
    color: #fff !important;
}

.btn-disabled {
    opacity: 0.6;
    cursor: not-allowed;
    background-color: #6c757d !important;
    color: #fff !important;
}

.instructions-content {
    margin-bottom: 2rem;
}

.instructions-content ul {
    padding-left: 1.5rem;
}

.instructions-content li {
    margin-bottom: 0.5rem;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding: 1rem;
    background-color: #f8f9fa;
    border-radius: 4px;
}

.timer {
    font-size: 1.1rem;
    font-weight: 600;
    color: #dc3545;
}

.progress {
    font-size: 1rem;
    color: #6c757d;
    text-align: center;
}

.answer-status {
    font-size: 0.9rem;
    color: #28a745;
    font-weight: 600;
    margin-top: 0.5rem;
}

.question-container {
    margin-bottom: 2rem;
}

.options-container {
    margin-bottom: 1.5rem;
}

.option {
    display: block;
    margin-bottom: 1rem;
    padding: 1rem;
    border: 2px solid #e9ecef;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s;
}

.option:hover {
    border-color: #007bff;
    background-color: #f8f9fa;
}

.option.selected {
    border-color: #007bff;
    background-color: #e3f2fd;
}

.option input[type="radio"] {
    margin-right: 0.5rem;
}

.skipped-indicator {
    background-color: #fff3cd;
    border: 1px solid #ffeaa7;
    color: #856404;
    padding: 0.75rem;
    border-radius: 4px;
    text-align: center;
    font-weight: 600;
    margin-top: 1rem;
}

.quiz-navigation {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
}

.center-buttons {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.user-summary,
.score-summary {
    background-color: #f8f9fa;
    padding: 1.5rem;
    border-radius: 4px;
    margin-bottom: 2rem;
}

.score-summary {
    text-align: center;
    font-size: 1.2rem;
}

.score {
    font-size: 2rem;
    font-weight: bold;
    color: #28a745;
}

.detailed-results {
    margin-bottom: 2rem;
}

.question-result {
    background-color: white;
    border: 1px solid #e9ecef;
    border-radius: 4px;
    padding: 1.5rem;
    margin-bottom: 1rem;
}

.question-result.correct {
    border-left: 4px solid #28a745;
}

.question-result.incorrect {
    border-left: 4px solid #dc3545;
}

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

.answer-comparison {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-top: 1rem;
}

.answer-box {
    padding: 1rem;
    border-radius: 4px;
    background-color: #f8f9fa;
}

.answer-box h4 {
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    color: #6c757d;
    text-transform: uppercase;
}

.answer-box p {
    margin: 0;
    font-weight: 600;
}

@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    
    .screen {
        padding: 1.5rem;
    }
    
    .quiz-header {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .quiz-navigation {
        flex-direction: column;
        gap: 1rem;
    }
    
    .center-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .center-buttons .btn {
        width: 100%;
    }
    
    .answer-comparison {
        grid-template-columns: 1fr;
    }
}