Make sticky headers when scrolling language columns

[ridhwaans]

Scrolling https://hyperpolyglot.org/scripting or https://hyperpolyglot.org/scripting2 for example when there are four different languages on screen, it becomes hard to differentiate which is which unless you are at the top of the page. Adding sticky headers that scroll with page identify the syntax language in question

[PatMyron]

duplicate of https://github.com/clarkgrubb/hyperpolyglot/issues/102