Colorscheme resets after Vim restart

[glow12121]

A question from a rookie.

I have installed gruvbox theme, then enabled it with colorscheme gruvbox and the scheme switched on just fine.

However, after I restart Vim, it looks like this:

[glow12121]

I think I got it - it was the scheme's light mode. Adding this line solved the problem:

set bg=dark    " Setting dark mode

[dufuhang]

I have same issue. But I don't know why I should set set bg=dark. Because according to this wiki, this settings is unnecessary. Bug maybe?

[nebelch]

The default value of background varies depending on the system and environment settings; see help 'background' in vim.