For perfect readability the of your display you should see every Line as a single pixel wide black and white line as well horizontally and vertically.

 

It is important that your browser is not zoomed, Browser Zoom must be 100%!

(Keyboard Shorcut  Firefox, Chrome, Explorer     CTRL+0   )

 

If you can't see perfectly seperated lines, there might be some setting active, either in your graphic card or in the display itself

 

To check the edges of your display you can switch to fullscreen browsing

(Keyboard shorcut  Firefox, Chrome, Explorer     F11   )

 

on the right edge of your Display you should see the vertical scrollbar, on the bottom edge of your display you should  see the horizontal scrollbar or the taskbar.