How can I change background colour for quotes, that was palced in another quote, like this?

thiscolour

quotetext

I think I must change it only with CSS. What code I need? Plase help.

This CSS code will do it...
Add it to Admin CP > Display > Colors > CSS Stylesheet.

Code:

blockquote div blockquote {
background : COLOR-NAME;
}

Thank you ankillien.

NO problem