style.css

body {
    min-height: 100%;
    display: flex;
}

table {
    border: 2px solid #000;
    margin: auto;
}

td {
    width: 50px;
    height: 50px;
    border: 1px solid #000;
    text-align: center;
    vertical-align: center;
    font-family: 'Courier New', Courier, monospace;
    font-size: 18px;
    position: relative;
}

td.pixel {
    width: 4px;
    height: 4px;
    border: 0;
}

.pixel-index {
    font-size: 10px;
    display: inline-block;
    position: absolute;
    top: 2px;
    right: 2px;
    color: #aaa;
}

button {
    background-color: brown;
    border: none;
    padding: 5px 20px;
}

.buttons {
    display: flex;
    justify-content: space-between;

    width: 300px;

    margin: 20px auto;
}

main {
    position: absolute;
    height:50px;
    left: 0;
    right: 0;
}