fix: collect definitions inside media queries

[jo16oh]

Currently, the CSS parser just skips media query blocks.
It should be updated to parse them to support use cases like the ones below.

@media (prefers-color-scheme: dark) {
  --color-text: white;
}

[jo16oh]

In addition, it's worth adding support for @property rules.

@property --logo-color {
  syntax: "<color>";
  inherits: false;
  initial-value: #c0ffee;
}

@property - CSS | MDN

[jo16oh]

close #42