If you are using `@starting-style` to animate the entry of a dialog+backdrop, there is no way to also animate the exit. There seems to be a proposal for an `overlay` property that only Chromium implements to far. This codepen showcases how you can do `transition: overlay 1s allow-discrete` to have an exit animation on the backdrop. See https://codepen.io/argyleink/pen/zYbQBOm for a complete example. Related to this, i filed https://bugs.webkit.org/show_bug.cgi?id=289473 for how dialog behaves on exit, without support for `overlay` atm.