html, body { 
    margin: 0; 
    padding: 0; 
    display: table; 
    width: 100%; 
    height: 100%;
    background: #000;
}
#container { 
    text-align: center; 
    display: table-cell; 
    vertical-align: middle; 
    height: 100%;
    width: 100%;
}
canvas { 
    background: #333;  
    width: 100%;
    height: 100%;
}