You might want to try Koreader, it allows you to turn Embedded Style on or off. It also has an option to "Set render style" with:
"clear all external styles"
Auto
chm.css
cr3.css
dict.css
doc.css
epub.css
fb2.css
htm.css
rtf.css
txt.css
You can tweak those and/or add your own to the list.
Luck;
Ken
You should also checkout tshering's "
Modifications for bad eyes" thread.