body {
    margin: 0;
    overflow: hidden;
    background: black;
    color: lime;
    font-family: 'Courier New', Courier, monospace;
    font-size: 16px;
}

.matrix {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    background: black;
}