Fix the intro text formatting on category pages

[tanius]

We added a custom feature that displays the full text of the "About the … category" topic at the top of a category page. Together with this, we adapted some CSS formatting on that page, such as making the category logo show smaller.

Something about this broke, so that now the text can overlap the category logo, as seen here. Due to the interference with numbered lists, we might not want the category logo to render as float: left at all, but rather in its own column-like space in the left. Starting with "Show more", the text would then again start at the very left.