body{
    background: #8E2DE2;  /* fallback for old browsers */
    background: -webkit-linear-gradient(to left, #4A00E0, #8E2DE2);  /* Chrome 10-25, Safari 5.1-6 */
    background: linear-gradient(to left, #4A00E0, #8E2DE2); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */
}

.img-container {
    margin: 0 auto;
  }

.img-container img {
    width: 400px;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}