body,
html {
  height: 100%;
  margin: 0;
}

.wrapper {
  background-image: url(../images/citylights.jpg);
  height: 100%;
  position: relative;
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
}

#logo {
  position: absolute;
  display: block;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}