Carregue CSS sempre que necessário

Javascript

function loadCSS(url) {
    var link = document.createElement("link");
    link.type = "text/css";
    link.rel = "stylesheet";
    link.href = url;
    document.getElementsByTagName("head")[0].appendChild(link);
}

jQuery

function loadCSS(url) {
    $("<link>", {
    rel: 'stylesheet',
    type: 'text/css',
    href: url
    }).appendTo('head');
}