Load css file without blocking rendering.

async-css.js

(function (s) {
    "use strict";
    var e,
        p;
    // Load CSS
    e = document.createElement("link");
    p = document.getElementsByTagName("head")[0];
    e.rel = "stylesheet";
    e.href = s;
    e.media = "only x";
    p.appendChild(e);
    setTimeout(function () {
        e.media = "all";
    });
}("all.css"));

// Minified:
(function(s){"use strict";var e,p;e=document.createElement("link");p=document.getElementsByTagName("head")[0];e.rel="stylesheet";e.href=s;e.media="only x";p.appendChild(e);setTimeout(function(){e.media="all";});}("all.css"));