Add find tool (ctrl+f) to cover page code

describe your feature request
On a repl’s cover page, you can view the code.
Basic text operations like copying are available, but some tools such as Find (ctrl+f) do not really work. The browser search is used by default, and since the file might not be entirely loaded at once, it misses some text.
Another example is Go to line number.

what problem(s) would this feature solve?
improve the experience of viewing others’ code without forking it

explain what you were trying to do when you came across the problem leading to this feature request
I often need to take a look at others’ code. Ctrl+F would be very useful in debugging on a cover page.