Actually it can't be solved. Firefox broke this possibility long time ago. They told us: use an addon (New tab override). It's an ungly solution to have an addon just for this purpose, but for some time it worked. But now, Firefox broke it again. New-tab-override offers to import my local file, but it can't display it the same way as it was before. I think I need to install a web-server on my machine - just to have a local file in new tab. How awesome is this? Besides this new-tab-override has a big problem with location-bar. If I open new tab then there is still the text of the location of new-tab-override. I can't just start typing a new url. I need to select all and delete first. It worked in Firefox 54, but guess what? Firefox broke this too. How can I go back to Firefox 3 or something. To the good old times where nothing was broken?