the black text over the white background, or a white text on the black background, is best for those with the viewing disabilities, and to display on the bad equipment. The grey text on the light background can give very poor contrast, grey text on dark background can also give very poor contrast, Some of the combinations such as black and red, black and blue, yellow and green always do strain the eye.

Text with the close letter spacing presents special difficulties for the readers who have vision problem. Text with extra letter spacing is easy to read. Where as text with the reduced letter spacing is difficult to read

The text with a good line spacing is easy to read. Text with the reduced line spacing is difficult to read.

The normal fonts are easy to read. Wher as Italic fonts are not so easy to read, so should use italic fonts less.