body {
  background: #000;
}
video {
	position: fixed;
	top: 0; 
	left: 0;
	min-width: 100%;
	min-height: 100%;
	width: auto;
	height: auto;
	z-index: -1;
}
p {
  font-family: serif;          
  color: #fff;
  font-size: 400%;
  margin: 50px;
  position: relative;
  z-index: 2;
}

.main-visual {
    height: 600px;
    background-size: cover;
    text-align: center;
    position: relative;
    overflow: hidden;
}
 
.main-visual img {
    z-index: 2;
    position: absolute;
    top: 100px;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    margin: auto;
}
 
.main-visual video {
    margin: 0 auto;
    z-index: 1;
    width: 100%;
}