@oldcoyote Looking good!
...except, the <baseline-status> adjusts for `prefers-color-scheme: dark` while your site doesn't leaving some users with the attached screen shot
Also, have thought about distribution of :not(:defined) styles to prevent a little FOUC in your <my-popover> element, something like:
my-popover:not(:defined) [slot="popover-content"] {
display: none;
}
Depends on usage whether it's worth having, especially without a standard distribution mechanism.