/* Added a comment for synchronization */
body {
    font-family: sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    background-color: #f0f0f0;
}

#game-board {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    margin-top: 20px;
}

.tube {
    width: 60px;
    height: 200px; /* 4 * 50px */
    border: 2px solid #333;
    border-top: none;
    border-bottom-left-radius: 30px;
    border-bottom-right-radius: 30px;
    margin: 10px;
    display: flex;
    flex-direction: column-reverse;
    cursor: pointer;
    transition: transform 0.2s;
    overflow: hidden; /* 水がチューブからはみ出さないように */
}

.tube.selected {
    transform: scale(1.1);
    border-color: #f00;
}

.water,
.empty-slot {
    width: 100%;
    height: 50px; /* 200px / 4 */
}

.empty-slot {
    background-color: #e0e0e0; /* 空のスロットの背景色 */
    border-top: 1px solid #ccc; /* スロット間の区切り */
}

#game-controls {
    margin-top: 20px;
}

button {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
}

.hidden {
    display: none;
}

#win-message,
#game-over-message {
    margin-top: 20px;
    text-align: center;
    padding: 20px;
    border: 2px solid #333;
    background-color: #fff;
    border-radius: 10px;
}