• HTML
• CSS

HTML

<h1>Nuestro Matrimonio</h1>

CSS

body{
    margin:0;
    min-height:100vh;
    background-image:url(valentine_2017.png);
    background-repeat:no-repeat;
    background-size:cover;
    background-position:center;
    background-attachment:fixed;
    
    display:flex;
    justify-content:center;
    align-items:center;
}

body:before{
    content:"";
    width:100%;
    min-height:100vh;
    position:absolute;
    top:0;
    left:0;
    
    background:linear-gradient(90deg,#52c4df,#ad55c1);
    
    opacity:0.7;
    z-index:-1;
}
h1{
    color:white;
    font-family:sans-serif;
}

/*
    Fuente: https://www.youtube.com/watch?v=4ghlSROVuH8
*/