Build popup should be smaller and have more padding when loading

[humitos]

This is a pretty minor issue.

I noticed the popup shown when hovering on a build shows a spinner icon that I think it would look better by reducing the width of it and increasing the padding for the icon so it doesn't touch the borders.

[agjohnson]

Note, this is going to be for all of the popupcards, most especially any doing async API interactions on hover.