src/angular-drag-drop.js
function loadStyles(css, doc) {
            // default to the global `document` object
            if (!doc) doc = document;

            var head = doc.head || doc.getElementsByTagName('head')[0];

            // no <head> node? create one...
            if (!head) {
                head = doc.createElement('head');
                var body = doc.body || doc.getElementsByTagName('body')[0];
                if (body) {
                    body.parentNode.insertBefore(head, body);
                } else {
                    doc.documentElement.appendChild(head);
                }
            }

            var style = doc.createElement('style');
            style.type = 'text/css';
            if (style.styleSheet) {
                // IE
                style.styleSheet.cssText = css;
            } else {
                // the world
                style.appendChild(doc.createTextNode(css));
            }
            head.appendChild(style);

            return style;
        }
function loadStyles(css, doc) {
            // default to the global `document` object
            if (!doc) doc = document;

            var head = doc.head || doc.getElementsByTagName('head')[0];

            // no <head> node? create one...
            if (!head) {
                head = doc.createElement('head');
                var body = doc.body || doc.getElementsByTagName('body')[0];
                if (body) {
                    body.parentNode.insertBefore(head, body);
                } else {
                    doc.documentElement.appendChild(head);
                }
            }

            var style = doc.createElement('style');
            style.type = 'text/css';
            if (style.styleSheet) {
                // IE
                style.styleSheet.cssText = css;
            } else {
                // the world
                style.appendChild(doc.createTextNode(css));
            }
            head.appendChild(style);

            return style;
        }
function loadStyles ( css , doc ) { // default to the global `document` object if ( ! doc ) doc = document ; var head = doc . head || doc . getElementsByTagName ( 'head' ) [ 0 ] ; // no <head> node? create one... if ( ! head ) { head = doc . createElement ( 'head' ) ; var body = doc . body || doc . getElementsByTagName ( 'body' ) [ 0 ] ; if ( body ) { body . parentNode . insertBefore ( head , body ) ; } else { doc . documentElement . appendChild ( head ) ; } } var style = doc . createElement ( 'style' ) ; style . type = 'text/css' ; if ( style . styleSheet ) { // IE style . styleSheet . cssText = css ; } else { // the world style . appendChild ( doc . createTextNode ( css ) ) ; } head . appendChild ( style ) ; return style ; }
Load styles into the head element

Source: https://github.com/webmodules/load-styles/blob/master/index.js
Load styles into the head element