.iframe-container {
  position: relative;
  width: 100%;
  height: 100%;
}

.iframe-container > iframe {
  display: block;
  width: 100%;
  height: 100%;
  border: none;
}

.view-source {
  font-family: Helvetica, Arial, sans-serif;
  position: fixed;
  bottom: 20px;
  right: 20px;
  padding: 8px;
  color: #fff;
  background: #121314;
  opacity: 0.7;
  font-size: 14px;
  transition: all .1s linear;
  border: 0;
}

.view-source:hover {
  opacity: 1;
}