" Simplistic way to make spaces and Tabs visible " This can be added to an already active syntax. syn match Space " " syn match Tab "\t" if &background == "dark" hi def Space ctermbg=darkred guibg=#500000 hi def Tab ctermbg=darkgreen guibg=#003000 else hi def Space ctermbg=lightred guibg=#ffd0d0 hi def Tab ctermbg=lightgreen guibg=#d0ffd0 endif