header {
  position: relative;
  background-color: black;
  height: 100vh;
  min-height: 25rem;
  width: 100%;
  overflow: hidden;
}
header video {
  position: absolute;
  top: 50%;
  left: 50%;
  min-width: 100%;
  min-height: 100%;
  width: auto;
  height: auto;
  z-index: 0;
  transform: translateX(-50%) translateY(-50%);
}
header .container {
  position: relative;
  z-index: 2;
}
header .overlay {
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  background-color: black;
  opacity: 0.1;
  z-index: 1;
}
#myBtn {
  margin-top: 50px;
  opacity: 0.5;
  width: 150px;
  border-radius: 10px;
}