Nested link styles in theme.json, specifically for text-decoration, is broken when using Gutenberg 18.1. This PR reduces the specificity of the global styles selector, wrapping everything in :where():

• Try reducing specificity of global styles selectors only. WordPress/gutenberg#60106

With that change in place, the Core CSS wins the specificity battle, overruling theme.json: https://github.com/WordPress/gutenberg/blob/trunk/packages/block-library/src/navigation/style.scss#L79-L88

Block library style updates were in included in this PR, but the Navigation block was not included:

• Reduce specificity of block library styles conflicting with block supports WordPress/gutenberg#59457