different display in left and right sidebars

Hello,

I don't exactly know whether it's a bug or a theme's normal feature but I noticed a weird behaviour in block's appearance.

When a block is populated by a view, displaying nodes' titles, the font style is different depending on which region the block is activated in : in left-sidebar, it appears "small" (like in every blocks which are not displaying nodes' titles), but in right-sidebar, it appears "big" (see screenshots 1 & 2 below). [the second block is a Quick Tabs' block but the source is exactly the same view]

Is that normal ? In fact, I really don't like it :-). It seems I can avoid it when right-sidebar is empty (collapsed), left-sidebar is then displayed in right (screenshot 3). But that's not very... flexible !
Do I have a better way to get round this behaviour ?

You may see other examples here http://www.drupalistic.net/module/flag ("Autour de ce module" block).

Thanks a lot !
Marie-Hélène