For the Instant App Portfolio Accordion style, we want to be able to use the Custom CSS feature to give a different background-color to each Section header based on our categories. I've used Chrome's inspect tool to find various class names, etc., but I cannot find a way to change the header background-color using CSS rather than the Primary, Secondary, and Accent options within the Theme & Layout settings. Is there a guide or specific CSS file that I can reference to know how to properly use the Custom CSS feature (which we love that Instant Apps now offer)?
