html {
  height: 100%;
}

body {
  height: 100%;
  background: gray;
}

.iframe-content {
  width: 90%;
  height: 75vh;
  margin: 9rem auto 0 auto;
}

.iframe-content iframe {
  width: 100%;
  height: inherit;
  margin-bottom: 3rem;
}

.header {
  background: gray;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 9rem;
  z-index: 1;
}

.button {
  text-decoration: none;
  text-align: center;
  display: inline-block;
  width:6rem;
  height:3.5rem;
  border-radius:9rem;
  background: black;
  font-size: 1rem;
  color: white;
  padding-top: 2.5rem;
  margin: 1.5rem 1rem;
}