html {
    height: 100%;
}

body {
    background-image: url('kt.jpg');
    background-size: cover;
    background-repeat: no-repeat;
    background-color: #000;
    height: 100%;
    padding: 0;
    margin: 0;
}

body > div {
    color: #eee;
    font-family: Arial, Tahoma, sans-serif;
    font-size: 3em;
    margin: auto;
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
}