I fixed it, looks like I miss placed “Gas Giant” and used some weird solution involving extending “Jovian Planets” by and extra rowspan (5!).
Many thanks!
P.s This MDN guide is amazing, im almost done with the first CSS module and its tiers better than my old books and HTML and CSS!
If you’re the one who compiled most of this then I just want to say that your guides rock and is beyond excellent!