How slick :is(this CSS!?)
removes the margins on all headers with a `.tight` class

h1.tight, h2.tight.......
:is(h1,h2).tight { }

Firefox
Safari
Chromium (coming soon!)
...rest https://caniuse.com/mdn-css_selectors_is

Here's a screenshot from Chrome Canary where it's supported with the chrome://flags/ #enable-experimental-web-platform-features enabled

Codepen https://codepen.io/argyleink/pen/abZvRbV