body {
    font-family: Arial, sans-serif;
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    background-color: #f0f0f0;
}

.container {
    background-color: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}

#start-screen {
    text-align: center;
}

#quiz-container {
    display: none;
}

#result-screen, #review-screen {
    display: none;
    text-align: center;
}

.button {
    background-color: #4CAF50;
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    margin-top: 20px;
    margin-right: 10px;
}

.button:hover {
    background-color: #45a049;
}

.question {
    margin-bottom: 20px;
}

.options {
    display: grid;
    gap: 10px;
}

.option {
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 5px;
    cursor: pointer;
}

.option:hover {
    background-color: #f0f0f0;
}

.option.selected {
    background-color: #e0e0e0;
}

#progress {
    margin-bottom: 20px;
}

.review-item {
    text-align: left;
    margin: 20px 0;
    padding: 15px;
    border: 1px solid #ddd;
    border-radius: 5px;
}

.correct-answer {
    color: #4CAF50;
    font-weight: bold;
}

.wrong-answer {
    color: #f44336;
    font-weight: bold;
}

.review-question {
    font-weight: bold;
    margin-bottom: 10px;
}

.review-options {
    margin-left: 20px;
}