Board Thread:Support Requests - Designing Your Wiki/@comment-31440879-20181110190559

As you can see at the bottom of the Minecraft Wiki Wikia.css, I have a couple dozen instances of a block of code that adds an image to the background of a page (e.g., this image to the Desert Biome article). The problem I am encountering is in the last example with the article 1.13 - The Update Aquatic. I know that the problem is because of the period in that name, but I do not know the alternative. I had guessed replacing the period with  as that is the code used in regular URL's, but it did not work. So, my question is: what is the correct way to reference that article's name? 