Rethinking Polaris web components after last night. Out of nowhere, the table header just disappears. No code changes on my end. That happens (or course) to coincide with a bug in my export. I was going to tell the customer, "hey, just use the filters for now". But, guess what? Filters are gone. I can't fix the web component b/c it is a black box. So, I apply a quick fix to move the filter out of the table header at the same time as fixing the export bug. Got it done. Profusely apologized. Crisis somewhat adverted. But my reputation with that customer is now damaged all for a few lines of CSS that I probably could have written myself. In retrospect, I think using a polaris css file with standard HTML components would have been better.