Here is a test of an embedded Strava activity:
There’s noting special about this particular run, I just picked it as an example to see what it looked like in my browser.
Here’s another example of an embedded map, this time from Google Maps:
Again, there is nothing special about this map — in fact, I’d be wary of using it, as it’s probably years out of date — I just picked it out from a bunch I made once. The point is to notice that the embedded map showed up.
One more embedded map, this time from Ride With GPS:
They all just seem to work, right? Contrast these with this one from Garmin:
If you have anything other than Firefox, you may see the embedded activity (inside the box I added for clarity), but if you’re using (a more modern version of) Firefox you should just see a gray line and a blank space in the box — Firefox is blocking what it now considers an insecure script coming from Garmin. I talked to Garmin tech support, and they say it’s a Firefox problem — that is, their insecure script is really a Firefox problem — and they won’t be fixing it.
This screws up about a half dozen pages here, and a few more on my old blog, and maybe even some other websites where I’ve embedded Garmin rides over the years. I think I may be going back and re-doing my ride pages in RideWithGps. Ugh, work… Oh well, lesson (re)learned: avoid counting on Garmin, especially their website.