vimdiff style color question: top & bottom lines

Question

I cannot find what the highlight name (or highlight group) is to change the guifg and guibg colors of the top and bottom lines in vimdiff. (The bottom line above the statusline, that is).

(More specifically, the lines with the "+--" at their left edge, to the right of the line number.)

In the attached screenshot, these are line numbers 1 and 18. (They're the lines with the bright silver background and cyan foreground colors.)

I would like to be able to change the colors of those lines in my vimrc.

I've looked through the Vim Reference Manual at everything I could find on highlighting and :highlight groups and have done several searches that have so far yielded no useful info.

Thanks for any insights.

Answer 1

Folded is the group responsible for those lines. See :help hl-Folded.

In the future, you can use :so $VIMRUNTIME/syntax/hitest.vim to try to visually find the matching group.