Pixel analysis of the user's screenshot confirmed the "second darker
line" below/above our bars is nvim's built-in horizontal window
separator. When `laststatus=3` (globalstatus=true), nvim draws `─`
between every pair of stacked windows using `fillchars.horiz` painted
with `WinSeparator.fg`. Nordfox's WinSeparator.fg is #232831 — dark —
which reads as a dim phantom row adjacent to our own bright sep.
On debug-mode enter, replace horiz/horizup/horizdown with space so nvim
has nothing visible to draw; our bars' own top/bottom separator rows
become the only visible chrome between them and neighboring panes. On
exit, restore the user's original fillchars.
swaits
c1c3143532