Style all letters on any webpage

I'd like to color all letters on any webpage without breaking scripts, styling entities etc. (if possible). It could be JS+CSS, but could be not.

I currently use JS+CSS in Greasemonkey, coloring select visible tag types by inserting tags per letter. I'm detecting page changes and coloring new elements. I also dropped in text-shadow for readability. The result is quite nice, but works partially and it's too slow (but not sluggish). Main problem is with text in divs, etc.

What for? Self-induced synesthesia seems to increase IQ permanently by 12 points on average. Synesthesia is mixing senses that some people experience constantly, weird example (whoah, weirder) is seeing letters in colors. Source: http://ift.tt/1OkAmk3 (end of page 4).