Improve tmux interoperability

.vimrc

@@ -334,6 +334,16 @@ set background=light
 exec "set <F24>=\<Esc>[O"
 exec "set <F25>=\<Esc>[I"
 
+" You might have to force true color when using regular vim inside tmux as the
+" colorscheme can appear to be grayscale with "termguicolors" option enabled.
+if !has('gui_running') && &term =~ '^\%(screen\|tmux\)'
+  let &t_8f = "\<Esc>[38;2;%lu;%lu;%lum"
+  let &t_8b = "\<Esc>[48;2;%lu;%lu;%lum"
+endif
+
+syntax on
+set termguicolors
+
 " Modify PaperColor to have white background
 let g:PaperColor_Theme_Options = {
            \   'theme': {