This bit of Javascript will activate the GitHub Enterprise styling on most GitHub pages.

gh.enterprise.js

(function(d) {
    d.body.classList.add('enterprise');
    var style = document.createElement('style')
    style.type = 'text/css'
    style.innerHTML = '.enterprise .header-logo-blacktocat:hover, .enterprise .top-nav a:hover, .enterprise #user-links a:hover, .enterprise .advanced-search:hover{color:#fff;text-shadow:0 0 10px #fff;}'
    d.getElementsByTagName('head')[0].appendChild(style);
})(document);