I found an article about Fandom saying that I should avoid inline CSS because it formats poorly on mobile. But that's not always the case. This template, on a wiki I frequent, has zero classes within it and is 100% incline CSS, yet formats fine on mobile.

Unless I'm viewing it from the template's page, in which case it looks like this

But this other template (that's also 100% inline CSS) doesn't render correctly on both it's template page

And in the mainspace

(BTW, it's supposed to look like this)

A few more details, the first one is made by only changing the background and text color and breaks, while the second one uses a flexbox to format the items.

So, what gives?