User blog comment:Trollocool/Styling your infoboxes/@comment-26402117-20160911142434/@comment-26575390-20160911152422

>Is it advisable to declare flex-basis as a larger value for .portable-infobox if the wiki has longish labels, or to declare a flex-basis specific to any theme?

It definitely is not advisable. The flex-basis property does not affect the infobox container (with the class .portable-infobox) at all (except for inheritance). What you are probably looking for is the usual width property. The flex-basis property is meant for elements inside a flex box.

TL;DR use width instead of flex-basis

Now to the question whether it is advisable assuming you use width:

It doesn't make a difference. Keep in mind that you need to use the additional CSS for .pi-image-thumbnail so the image scales properly. Aside from that I would only recommend adjustments for the flex-basis property values, so they match the new width.

>Do you think .pi-caption should be italicised for captions by default?

I, myself, prefer using normal text without additional text decorations like italic and underline. It just looks better to me. But this is only my opinion, there is no general answer to it, because some people are used to italic captions and like it better, while others prefer no decorations.

>How would one go about building a themesource with corresponding CSS for a wiki with more complex PIs than mine, and what stages would it involve?

Well, I usually develop my CSS in following steps if I need theme-sources:

1. Find similarities between all infoboxes. Depending on the wiki's unification level of its infoboxes, there is more or less CSS that goes here. As you spoke of complicated examples, maybe only widths, font sizes, font weights, text aligns and line heights go here, if not even less. This CSS is applied to very unspecific PI selectors like .portable-infobox and .pi-europa.

2. Create CSS for every theme of your wiki. The CSS defined with the theme attribute (as in