body {
    font-family: Arial, sans-serif;
}

h1 {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

#mode-select {
    font-size: inherit;
    font-family: inherit;
    font-weight: bold;
    border: none;
    border-bottom: 2px solid #333;
    background: transparent;
    cursor: pointer;
    outline: none;
    padding: 0 2px;
    appearance: none;
    -webkit-appearance: none;
    text-align: center;
    width: 1.2em;
}

#mode-select:hover {
    color: #444;
    border-bottom-color: #888;
}

#box {
    width: 700px;
    height: 450px;
    background-color: yellow;
    border: 5px solid black;
    position: relative;
}

#redball {
    width: 20px;
    height: 20px;
    background-color: red;
    border-radius: 10px;
    position: absolute;
}

#blueball {
    width: 20px;
    height: 20px;
    background-color: blue;
    border-radius: 10px;
    position: absolute;
}

.food {
    width: 10px;
    height: 10px;
    border-radius: 5px;
    background-color: green;
    position: absolute;
}