* {
  margin: 0px;
  padding: 0px;
}

h1 { font-size: 3em; }

.bg {
  position: relative;
  z-index: -1;
  height: 500px;
  background-image: url('https://unsplash.it/1278/500/?random');
  background-repeat: no-repeat;
  background-size: cover;
  background-size: 100% 100%;
}

#content {
  height: 600px;
  width: 100%;
  background-color: rgba(51,204,204,.5);
  position: relative;
  margin-top: -20px;
  z-index: 1;
}