Cant change textarea line height. I can change font size using quasar/tailwind classes or using css style, but line-height is still the same (even using line-height css style).

When user types, it calculates the width/height of the hidden element and copies it to the textarea. Because of this dynamic, you can not style your textarea during expansion and expect it to continue ...

I think your best chance is to statically size the textarea AND the related divs using CSS. You don't have to use ems; you could use pixles whichever works better for you situation.