I love SMIL. Have been using it to craft custom SVG loaders for almost every brand I've worked with. Loader is usually much smaller than a gif, vector, animated 60 FPS, etc. So good.
Do you have any resources on how you learned to create such loaders? I hacked together a custom loading animation for some tools I've built just using images & css transforms, but would love to learn to make things even slicker.