header {
  -webkit-box-align: center;
      -ms-flex-align: center;
          align-items: center;
  background: #000 url(../images/moon.jpg) center no-repeat;
  background-size: 100% auto;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  height: 100vh;
  -webkit-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
  overflow: hidden;
  position: relative;
  width: 100vw;
}

header:after {
  background: -webkit-linear-gradient(top, rgba(0,0,0,0), rgba(0,0,0,1));
  background: linear-gradient(to bottom, rgba(0,0,0,0), rgba(0,0,0,1));
    bottom: 0;
  content: "";
    left: 0;
  position: absolute;
    right: 0;
    top: 0;
}

.example-logo {
  z-index: 10;
}

.heading {
    bottom: 10vh;
  color: white;
  font-size: 10em;
    left: 0;
  line-height: 1;
  margin: 0;
  position: absolute;
    right: 0;
  text-align: center;
}

.content {
  position: relative;
}

.content p {
  -webkit-transform: translateZ(0);
          transform: translateZ(0);
  z-index: 10;
}

.floating-rocks {
  position: absolute;
}

.front-one {
  right: -10em;
}

.front-two {
  left: -12em;
}

.back-one {
  left: -4em;
  opacity: .2;
  z-index: 0;
}

.back-two {
  opacity: .1;
  right: -20em;
  z-index: 0;
}

.planet-earth {
  border-radius: 50%;
  left: -5em;
  opacity: .8;
  z-index: 0;
}

footer {
  background: url(../images/moon2.jpg) top center no-repeat;
  background-size: cover;
  height: 1014px;
  margin-top: 10em;
  position: relative;
}

footer .heading {
  bottom: auto;
  color: rgba(0,0,0,1);
  top: 40%;
}

.credit {
    bottom: .5em;
  font-size: 1.75em;
    left: 0;
  margin: 0;
  position: absolute;
    right: 0;
  text-align: center;
    top: auto;
}