Is Wikipedia one of your bookmarked websites? If so, you should check out the Wikiwand add-on for Firefox. That’s an add-on which revamps the Wiki pages with new menus and enhanced formatting.
To add Wikiwand to Firefox, open this page  and click the + Add to Firefox > Install Now buttons. Once added to Firefox, the page in the shot below opens. Now head over to the Wikipedia website.
When you open a page in Wiki it will be more like the one below. So now some of the pages include expanded images as large cover photos at the top of the page. The pages also have a great new modern typography.
However, it’s perhaps the navigation menu on the left that is the most notable addition to the revamped Wiki. That replaces the content links at the top of the Wiki pages. As such, you can now jump to page headings by clicking their links on the navigation menu instead. To remove the navigation menu, click the small icon at the top left of the page.
Another new addition to the Wiki pages are the link previews. Hover the cursor over a page link to open a preview of it as below. Click the icon at the bottom left of the preview window to go to the page.
The revamped pages also have a few customization options that you can open by clicking the Personalize button at the top. That opens the window below from which you can select an alternative font, background color or text size. Drag the bars to the right to switch to a Sans font and black background as below.
Overall, Wikiwand gives Wiki a considerable revamp. You can also add the extension to Google Chrome. Just click here  to download and install the Wikiwand extension for Chrome.