fix: remove root from media queries

[montezume]

To make our media queries compatible with version 7 of postcss-custom-media.

After this is merged and released, we will update our webpack-config in merchant-center-application-kit to

postcssCustomMediaQueries({
  preserve: false,
  importFrom: [
    require.resolve(
      '@commercetools-frontend/ui-kit/materials/media-queries.mod.css'
    ),
  ],
}),

and update postcss-custom-media to version 7.0.6 (important), and remove the resolution for version 6 in the MC.

and then we can remove all of the @import's of media queries in the MC.

[emmenko]

Sounds like a plan! 💯