Firefox offers support for alternative style sheets. Pages that provide alternative style sheets allow the user to select the style in which the page is displayed using the View>Page Style submenu. This provides a way for users to see multiple versions of a page, based on their needs or preferences.
A web page can use the <link> element to add alternative style sheets to a document.
Go to the View>Page Style submenu and select a different style to watch this page's look change!