Well, let me rephrase my problem...
I want to set up font-style to be normal for all text which appear in sidebars.
On the right sidebar, I'm using only RSS widgets (
Blogging4Change). For the first two RSS widgets, I have defined only the RSS feed URL, text is displayed as link and it wasn't hard to define font family, weight, style, color... For the third, fourth and fifth widgets, beside putting the RSS feed URL, I've also checked option "Display item author if available?", and displayed text (which is not link) for that option is italic (font-style). I need to make it normal font-style.
I guess that it'll be sufficient to add HTML/CSS inserts.
Thanks one more for helping me!