Setting fela styles to elements found by selectors similarly to CSS ones,
but root "classes" or argument props, if not used with lit-css, are TAG selectors.
To find some more complex stuff, use modifiers like .div.thisClass:hover
etc.
It's safe to leave it as is during SSR, 'cause there's a check inside,
but it won't appear in SSR rendered stylesheet. Also it is not reactive. Yet.
// main.js
import { Renderer } from 'fela-vue'
const renderer = new Renderer()
renderer.setClasses(css`
.html, .body {
margin 0
padding 0
font-size 18px
}
`)