#button-container {  
    width: 6em;
    height: 6em;
    margin: 1.5em auto;
    border: 0px solid #000;
    border-radius: 50%;
    background-size: cover;  
    box-shadow: 0 0.5em 0.5em rgba( 0, 0, 0, 0.3 ), 
                0.5em 0 0.5em rgba( 0, 0, 0, 0.3 ),
                0 -0.5em 0.5em rgba( 0, 0, 0, 0.3 ), 
                -0.5em 0 0.5em rgba( 0, 0, 0, 0.3 );
 } 

#button {
    display: block;
    width: 100%;
    height: 100%;
    margin: 38% auto;
    border: 1px solid #000;
    border-radius: 50%;
    background-color: rgba( 0, 0, 0, 0.5 );
    background-image: url(play-pause.png);
    background-size: 100% auto;
    cursor: pointer;
 }

.pause {
    background-position: 0 -100%;
 }

.hide { 
    display: none;
 }

.remove {
    position: absolute;
    left: -999em;
 }