style.css

body
{
    margin: 0;
    font-family: sans-serif;
    background: #333;
    overflow: hidden;
}
canvas
{
    vertical-align: middle;
    margin: auto;
    display: block;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
}
.buttons
{
    position: absolute;
    left: 10px;
    right: 10px;
    top: 10px;
    width: 440px;
    margin: auto;
    background: #222;
    padding: 10px 0 0 10px;
    border-radius: 5px;
    box-sizing: border-box;
}
button,
input
{
    float: left;
    min-width: 30px;
    height: 30px;
    padding: 0 10px;
    border: none;
    margin: 0 10px 10px 0;
    box-sizing: border-box;
    text-align: center;
    background: crimson;
    color: white;
    font-weight: bold;
    font-family: sans-serif;
    outline: none;
    border-radius: 3px;
}

button
{
    width: 125px;
}

.size,
.seed
{
    width: 75px;
    background: white;
    color: black;
}

.seed
{
    width: 245px;
}

.zoom
{
    float: right;
    width: 30px;
    height: 30px;
    padding: 0;
}