In my opinion, a common practice is to always ensure that when using a plugin, its corresponding CSS file is also included.
One approach could be to have your jQuery plugin handle this automatically:
$('head').append('<link rel="stylesheet" href="/css/myPlugin.css" />');
Alternatively, you can check if the stylesheet is already included before adding it:
if (!$('head>link[href$="myPlugin.css"]').size()) // if the stylesheet isn't already included
$('head').append('<link rel="stylesheet" href="/css/myPlugin.css" />');
For better organization, consider creating a separate plugin for managing stylesheets:
$.extend({addStyleSheet : function (nameOfPlugin) {
if (!$('head>link[href$="' + nameOfPlugin + '.css"]').size()) // if the stylesheet isn't already included
$('head').append('<link rel="stylesheet" href="/css/' + nameOfPlugin + '.css" />');
});
Then within your main plugin, simply call this function like so:
$.addStyleSheet('myPlugin');