ty:is(.a99) {
//     --x0: a b c d e f g;
//     --x1: a b c d e f g;
//     ...
//     --x9: a b c d e f g;
//   }
// }
//
// Each nested rule looks like a declaration, because it's an ident followed by
// a colon. This case can be optimized by an implementation that recognizes
// early (enough) that not-a-property is not a known property.
function makeStyle() {
  let rules = [];

  for (let i = 0; i < RULES; i++) {
    rules.push(`
      not-a-property:is(.a${i}) {
        ${[...Array(DECLARATIONS_PER_RUL