body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    background-color: #f4f4f4;
    color: #333;
}

.container {
    background-color: #fff;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    text-align: center;
    width: 90%;
    max-width: 500px;
}

h1 {
    color: #0056b3;
    margin-bottom: 20px;
}

.controls {
    margin-bottom: 20px;
}

#volume-slider {
    width: 80%;
    margin-top: 10px;
}

#audio-visualizer {
    width: 100%;
    height: 150px;
    background-color: #eee;
    border: 1px solid #ccc;
    margin-top: 20px;
}

/* スマートフォン対応 */
@media (max-width: 600px) {
    .container {
        width: 95%;
        padding: 15px;
    }

    #volume-slider {
        width: 90%;
    }
}