Skiplinks are a way to bypass large parts of page elements. For keyboard users this is a method to quickly reach the content of a page.
Put the HTML-code in your HTML-template. Put the CSS-code in your CSS-file.
Use it as you like, as long as you don't put a patent on it.
Use the tab-key to see what happens (Tab is forward, Shift+Tab is backward)
Jules Ernst 200 OK