#canvas {
    position: relative;
    background-color: #000;
}

#player, #enemy {
    position: absolute;
    width: 20px;
    height: 20px;
}

#player {
    background-color: #1030de;
}

#enemy {
    background-color: #de0000;
}

#control {
    margin-top: 0.4em;
}

#btn-start, #btn-stop {
    border: solid 1px #a9a9a9;
    padding: 0.3em 0.8em;
    background-color: #f9f9f9;
    font-size: 1.1em;
    font-weight: bold;
    color: #303030;
}

#btn-stop {
    margin-left: 0.4em;
}