html,
body {
    height: 100%;
    margin: 0;
    padding: 0;
    background-color: #007FFF;
}

h1 {
    font-family: Arial, Helvetica, sans-serif;
}

.img-container {
    text-align: center;
    width: 500px;
    height: 500px;
    position: absolute;
    left: 50%;
    top: 50%;
    margin-left: -250px;
    margin-top: -250px;
}

img {
    margin: auto;
}