.overlay { height:100%; width:0; position:fixed; z-index:3; top:0; left:0; background-color:rgba(0,0,0, 0.8); 
           overflow-x:hidden; transition:0.5s; }
.overlay-content { position:relative; top:10%; width:100%; }
.overlay-column h3 { margin-bottom:2px; font-size:1.5em; color: #FFFFFF; transition: 0.3s; }

/* Create three equal columns that floats next to each other */
.overlay-column { float:left; width:15%; padding:5px; height:200px; }

/* Clear floats after the columns */
.overlay-row:after { content:""; display:table; clear:both; }
.overlay a { text-decoration:none; display:block; text-align:left; font-size:1.2em; color:#818181; transition:0.3s; }
.overlay a:hover, .overlay a:focus { color: #f1f1f1; }
.overlay .closebtn { position:absolute; top:3%; right:2%; font-size:50px; }

@media screen and (max-width: 600px) {
  .overlay-column { width:100%; height:auto; }
}