body {
    font-family: Arial, sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    margin: 0;
    background-color: #f0f0f0;
}

h1 {
    color: #333;
    margin-bottom: 30px;
}

.score-area {
    font-size: 20px;
    font-weight: bold;
    margin-bottom: 20px;
    color: #555;
}

#score {
    color: #007bff;
}

.game-container {
    display: flex;
    align-items: center;
    gap: 20px;
}

.car {
    position: relative;
    width: 150px;
    height: 80px;
    background-color: #4CAF50; /* 車の色 */
    border-radius: 10px;
    box-shadow: 0 5px 10px rgba(0,0,0,0.2);
}

.car .window {
    position: absolute;
    top: 10px;
    left: 20px;
    width: 110px;
    height: 40px;
    background-color: #fff;
    border-radius: 5px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    font-weight: bold;
    color: #333;
}

.car .body {
    position: absolute;
    bottom: -20px;
    left: 0;
    width: 100%;
    height: 20px;
    background-color: transparent;
}

.car::before, .car::after {
    content: '';
    position: absolute;
    bottom: -20px;
    width: 40px;
    height: 40px;
    background-color: #333;
    border-radius: 50%;
    z-index: -1;
}

.car::before {
    left: 15px;
}

.car::after {
    right: 15px;
}

.operator {
    font-size: 40px;
    font-weight: bold;
    color: #555;
}

#answer-input {
    width: 100%;
    height: 100%;
    border: none;
    text-align: center;
    font-size: 24px;
    font-weight: bold;
    background: transparent;
    box-sizing: border-box;
}

.button-container {
    margin-top: 30px;
    display: flex;
    gap: 15px;
}

#check-button, #next-button {
    padding: 10px 20px;
    font-size: 20px;
    cursor: pointer;
    background-color: #007bff;
    color: #fff;
    border: none;
    border-radius: 5px;
    transition: background-color 0.3s;
}

#check-button:hover, #next-button:hover {
    background-color: #0056b3;
}

.result-message {
    margin-top: 20px;
    font-size: 24px;
    font-weight: bold;
}

.correct {
    color: #28a745; /* 緑色 */
}

.incorrect {
    color: #dc3545; /* 赤色 */
}