body {
  margin: 0;
  padding: 0;
  overflow: hidden; }

#coverBlack {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 1;
  width: 100%;
  height: 100%;
  opacity: 1.0;
  background: #000000; }

footer{
    width: 100%;
    background-color: #000;
    color: #fff;
    text-align: center;
    padding: 30px 0;

 position: absolute;/*←絶対位置*/
    bottom: 0; /*下に固定*/
}