style.css

html, body
{
    margin: 0;
    padding: 0;
    font-family: Arial;
    font-size: 12px;
    color: white;
    background: black;
    -webkit-text-size-adjust: none; /* important, or your text resizes randomly on rotation! */
    -webkit-tap-highlight-color: transparent;
}

#game_canvas
{
    z-index: 1;
    overflow: hidden;
    image-rendering: optimizeSpeed;
    -webkit-tap-highlight-color: transparent;
    -moz-tap-highlight-color: transparent;
    -webkit-user-select: none;
    -webkit-transform: translateZ(0);
    -ms-touch-action: none;
}

canvas
{
    z-index: 1;
    overflow: hidden;
    image-rendering: optimizeSpeed;
    -webkit-tap-highlight-color: transparent;
    -moz-tap-highlight-color: transparent;
    -webkit-user-select: none;
    -webkit-transform: translateZ(0);
}


#wrong_orientation
{
    background: black;
    position: absolute;
    top: 0px;
    left: 0px;
    z-index: 2;
    width: 100%;
    height: 100%;
    display: none;
}

#wrong_orientation img
{
    display: block;
    margin: 0 auto;
    width: 80%;
}