The full docs on MDN https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values/basic-shape/shape
And a handy tool to convert SVG paths https://css-generators.com/svg-to-css/
Here's the heart demo https://random-stuff.jakearchibald.com/heart-css-shape/
Note that the :hover applies to a wrapper, otherwise the clipped area is used for hit-testing - an old gotcha reminiscent of the Flash days.
@petafloppa could be fun for animation!
In Firefox and Chrome, you can use SVG, but override the path using the `d` property in CSS https://developer.mozilla.org/en-US/docs/Web/SVG/Reference/Attribute/d - but unfortunately it doesn't work in Safari.
@petafloppa that’s also what I thought about ☺
Having icons that work everywhere without custom fonts or inlined SVG data URI could make stuff much nicer.
@firefoxwebdevs