html, body {
    width: 100%;
    height: 100%;
}
body {
    background-color: #ffffff;
    margin: 0;
    overflow: hidden;
    font-family: arial;
}
#blocker {
    position: absolute;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
}
#instructions {
    width: 100%;
    height: 100%;
    display: -webkit-box;
    display: -moz-box;
    display: box;
    -webkit-box-orient: horizontal;
    -moz-box-orient: horizontal;
    box-orient: horizontal;
    -webkit-box-pack: center;
    -moz-box-pack: center;
    box-pack: center;
    -webkit-box-align: center;
    -moz-box-align: center;
    box-align: center;
    color: #ffffff;
    text-align: center;
    cursor: pointer;
}