We're preaching UI-Standardization to developers, but ApiSandbox is still using jQuery UI gradient buttons.
This is also a chance to fix the bug where the [Make request] [Examples] [Clear] buttons obscure the h6 action name.
F95551 is a quick mockup using mediawiki.ui styles to make the buttons left-aligned with one primary action per the style guide, and it puts the action in the table heading. For super-duper XP, could/should switch to OOUI widgets. I'm not sure what to do with the old-school <fieldset><legend> lines around each section.