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

body {
  background: #7f7fd5; /* fallback for old browsers */
  background: -webkit-linear-gradient(to right, #7f7fd5, #86a8e7, #91eae4); /* Chrome 10-25, Safari 5.1-6 */
  background: linear-gradient(to right, #7f7fd5, #86a8e7, #91eae4); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */
}

#logo {
  width: 250px;
  height: 250px;
}