The kind folks at iNaturalist.org identified this one for me — I was looking in entirely the wrong family. This lovely lady is a tuft-legged (or tuftlegged) orbweaver spider, Mangora placida, with the definitive feature, I think, being those two white spots on her abdomen, along with the shape of the dark brown stripe they’re in. The dark brown stripe on her carapace widens toward the head, which it does not do in other members of the genus.
These little spiders range over most of North America (including Florida, who knew) and that the species was first described by Hentz in 1847.
Orbweaver spiders, in general, make the traditionally-shaped spider webs you see in cartoons and comics. The tuftlegged orbweaver makes a similar web, except with a smaller/finer “weave”, so to speak, which can catch tiny prey. The hairs (setae) on its legs allow the spider to navigate its web without ruining the lines.
Spiders in the genus Mangora have tiny, feathery hairs called trichobothria on the front of the tibia of leg III, which is helpful to know, except that they can only be seen in really up close photos (certainly not the one above). Here they are under a microscope, courtesy of bugguide. (As the page says, “Works great when the specimen is dead!”)