Nerd Font – why is the first glyph larger? Feature or bug?

[gadefox]

I'm using fish with the following greeting:

function fish_greeting
  echo
  for c in black red green yellow blue magenta cyan white
    set_color $c
    echo -n " "
    set_color br$c
    echo -n " "
  end
  echo
end

I like this feature—or maybe bug? It’s odd, but the first glyph in each pair sometimes renders slightly larger than the second in Kitty, even though they are identical Nerd Font symbols.

The problem becomes more obvious when using nnn, as you can see in the attached screenshot: the misaligned glyphs make the file icons appear uneven. Any idea?? Thanks

.

[kovidgoyal]

Read the first entry in the kitty FAQ

[gadefox]

Thanks a lot, at least I know it's a feature *.
Anyway, as you can see there is a space after the glyph:

if (ent->flags & FILE_SELECTED)
#if defined(NERD)
      addstr("");
#else
      addch('+' | A_REVERSE | A_BOLD);
#endif
    else
      addch(' ');
addch(' ');

*The exception is if these characters are followed by a space or en-space (U+2002) in which case kitty makes use of the extra cell to render them in two cells.

[kovidgoyal]

I cant see any such thing. You dont need a C program to test this, here you go:

Big small with space and without, exactly as expected.