Test M
Inline SVG. A ring, a line, and a dot that should be pulsing on its own. Note that uploading an SVG file is refused by the asset API, but inline SVG is a different path and may well survive.
Test N
Does JavaScript run? If the box below turns green and says EXECUTED, then everything is on the table and the Mighty embeds could be rebuilt natively. If it still says the red text, scripts are stripped and CSS is the ceiling.
SCRIPT DID NOT RUNTest O
Sticky positioning and filters. The bar below should have a blurred, semi transparent backdrop if backdrop-filter is supported.
Backdrop filter testTest P
Web fonts. The line below asks for a Google font over the network. If it renders in a distinctly different typeface, remote fonts load and custom typography is possible. If it looks like the surrounding text, external font loading is blocked.