*,
::before,
::after {
  box-sizing: border-box;
}

body {
  font-family: sans-serif;
  background: #000;
  color: #ddd;
  margin: 0;
}

main {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 100%;
  padding: 1rem;
  transform: translate(-50%, -50%);
  text-align: center;
}

main>h1,main>p,footer>p {
  max-width: 30rem;
  margin-left: auto;
  margin-right: auto;
}

footer {
  position: absolute;
  bottom: 0;
  width: 100%;
  font-size: .8rem;
  text-align: center;
}

.flash {
  font-weight: bolder;
  font-size: .8rem;
  color: #aaa;
  animation: flash 3s infinite;
}

@keyframes flash {

  from,
  50%,
  to {
    opacity: 1;
  }

  25%,
  75% {
    opacity: 0;
  }
}

/**
Space Travel Animated Background
Credit to https://misspriyankadas.medium.com/space-travel-animation-using-html-and-css-676f4232754c
*/
#space,
.stars {
  overflow: hidden;
  position: absolute;
  z-index: -1;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
}

.stars {
  background-image:
    radial-gradient(2px 2px at 20px 30px, #eee, rgba(0, 0, 0, 0)),
    radial-gradient(2px 2px at 40px 70px, #fff, rgba(0, 0, 0, 0)),
    radial-gradient(2px 2px at 50px 160px, #ddd, rgba(0, 0, 0, 0)),
    radial-gradient(2px 2px at 90px 40px, #fff, rgba(0, 0, 0, 0)),
    radial-gradient(2px 2px at 130px 80px, #fff, rgba(0, 0, 0, 0)),
    radial-gradient(2px 2px at 160px 120px, #ddd, rgba(0, 0, 0, 0));
  background-repeat: repeat;
  background-size: 200px 200px;
  animation: zoom 4s infinite;
  opacity: 0;
}

.stars:nth-child(1) {
  background-position: 50% 50%;
  animation-delay: 0s;
}

.stars:nth-child(2) {
  background-position: 20% 60%;
  animation-delay: 1s;
}

.stars:nth-child(3) {
  background-position: -20% -30%;
  animation-delay: 2s;
}

.stars:nth-child(4) {
  background-position: 40% -80%;
  animation-delay: 3s;
}

@keyframes zoom {
  0% {
    opacity: 0;
    transform: scale(0.5);
    animation-timing-function: ease-in;
  }

  85% {
    opacity: 1;
    transform: scale(2.8);
    animation-timing-function: linear;
  }

  100% {
    opacity: 0;
    transform: scale(3.5);
  }
}