body,div,html{display:grid;justify-items:center;align-content:center;margin:0;padding:0;overflow-x:hidden}button.btn{position:fixed;margin:5px;width:55px;height:55px;color:#fff;font-weight:700;border-radius:5px;font-size:25px;opacity:.66}iframe{width:100vw;height:100vh}