Unnecessary (and odd) background for some highlight groups

[cdelledonne]

Problem

Some highlight groups define a background color that seems unnecessary, and that overrides the color of some other elements, like the cursorline. This happens with Normal, htmlBold*, htmlItalic, htmlUnderline*, and probably some others too.

As an example, here's what happens for these highlight groups when they are in the cursorline:

The background of the last word overrides the background of the cursorline. I would expect these highlight groups to blend in with the rest, possibly not defining any background color.

Environment

• Nvim v0.4.3
• Tmux inside Alacritty terminal emulator
• No gruvbox_256palette.sh
• Minimal .vimrc (uses vim-plug)

  call plug#begin('~/.local/share/nvim/plug')
  Plug 'gruvbox-community/gruvbox'
  call plug#end()
  set cursorline
  set termguicolors
  let g:gruvbox_contrast_dark = 'hard'
  colorscheme gruvbox

To reproduce

Start editing an empty buffer, and paste the following text at the beginning of the buffer:

Highlight as: Normal
Highlight as: htmlBold
Highlight as: htmlItalic
Highlight as: htmlUnderline

Then, manually apply some highlight to the last word of each line. For instance, inside nvim, run the following 4 commands:

:call nvim_buf_add_highlight(0, -1, 'Normal', 0, 14, -1)
:call nvim_buf_add_highlight(0, -1, 'htmlBold', 1, 14, -1)
:call nvim_buf_add_highlight(0, -1, 'htmlItalic', 2, 14, -1)
:call nvim_buf_add_highlight(0, -1, 'htmlUnderline', 3, 14, -1)