#cover { position:absolute; top:0; left:0; padding:0; margin:0; width:100%; height:100%; background-color:#000; font-family:sans-serif; line-height:1.15; }

#require            { display:table; position:relative; margin:auto; z-index:99; width:85%; top:20%; height:20%; border-radius:10%; text-align:center; color:#fff; font-size:calc(3 * (1vw + 1vh - 1vmin)); font-weight:bold; }
#require div.footer { display:table; margin:20px auto; width:100%; }
#require button     { width:38%; margin:3% 5% 2% 5%; padding:10px 1px; color:#e80; border-radius:10px; font-size:calc(2.5 * (1vw + 1vh - 1vmin)); font-weight:bold; text-transform:uppercase; background-color:#fff; cursor:pointer; }