JSFiddle - React, Tailwind, and code Playground

CSS

html,body {height:100%;width:100%;}
body {
    background: url("http://responsive.gs/images/bg-phoenix.jpg") no-repeat;
    background-position: center top;
    -webkit-background-size: cover;
    background-size: cover;
}

JavaScript

var img = new Image();
img.src = "http://responsive.gs/images/bg-phoenix.jpg";

$(window).on("resize", function () {
    $('body').height($('body').width() * img.height / img.width);
}).resize();