You should be able to utilize the asterisk and !important
elements within CSS.
html *
{
font-size: 1em !important;
color: #000 !important;
font-family: Arial !important;
}
The asterisk matches everything (you could probably get away without the html
too).
The !important
ensures that nothing can override what you've set in this style (unless it is also important). (this is to help with your requirement that it should "ignore inner formatting of text" - which I took to mean that other styles could not overwrite these)
The rest of the style within the braces is just like any other styling and you can do whatever you'd like to in there. I chose to change the font size, color and family as an example.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…