html {
    background-image: url('https://64.media.tumblr.com/9f6f28c691d842a8dc6345084779644d/b177114c95a2726f-f7/s500x750/2afca61962b2859d9c13b128be140f1f97601d8e.gif');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    min-height: 100vh;
}
body { 
    background-color:black; 
    font-family: -apple-system, BlinkMacSystemFont, sans-serif;
    border: 10px solid black; 
    border-color:black; 
    color:white; 
    padding: 20px 20px 20px; 
    width: 50%; 
    margin:auto;
    box-sizing: border-box;
text-align: center}