I would like to have more space between the item-markers (the pink stripes) in the widget Recent posts. See on the right of my homepage. I would like to do the same for the menu on the left.

In the Style widgets (ATO) you can only adjust the left padding. I tried to put in some CSS:

#recent-posts-3 li {
padding-bottom: 7px;
}

But that only results in more space between the linktext.

You need to use margin instead of padding and add !important. For example.

#recent-posts-3 li {
    margin-bottom: 15px !important;
}

Thanks, I found out my mistake just after posting ...