Please name your favourite I-used-to-do-this-with-JavaScript-but-now-I-don't-need-to CSS properties/functionalities.
@ppk coming up: field-sizing https://caniuse.com/?search=field-sizing
"The field-sizing CSS property allows form controls such as <textarea> to be sized based on their content."
Right now auto-growing an input box with the content inside it requires some artful CSS layering and a sprinkle of JS
https://css-tricks.com/the-cleanest-trick-for-autogrowing-textareas/