body {
    background-color: #222;
    color: white;
}

.choice-btn {
    padding: 5px 10px;
    border-radius: 3px;
    border: 1px solid black;
    margin: 2px;
}

.choice-btn:hover {
    background-color: #ccc;
}

.choice-div {
    border: 1px green solid;
}

.node-div {
    border: 1px red solid;
}

#content {
    width: 500px;
    margin: auto;
}