Hi, I really like shadow4, but I hate the red colored weekends and the white colored "today" is there any way to modify something in order to get rid of those? Thanks

In case there is not: Is there any "transparent" skin, that has a week view? I've been searching all day but I just can't find anything.

Welcome to the forum, Idefix.

Are you talking about the week view from shadow4 when you say "white colored today", right? First I suppose that you were talking about the calendar only.

If you don't like the colors and want to edit them, you need to unzip the Shadow4.r2skin file and edit the /images/grid-bg-*.png files (today and weekend, in your case) with any app which supports alpha channel, and then zip all again. Keep a copy of the files to avoid doing this again if the skin is updated or something like that.
www.rainlendar.net/cms/index.php?option=com_easyfaq&Itemid=26#faq6