CSS reset fixes

[cemms1]

The CSS reset used in DCR is much more aggressive than in frontend, causing a number of CSS issues due to specificity.

We ought to decide a general fix for these to ensure future issues are more easily solved.

Relevant PRs:

• Exponent notation not showing in AMP #8361
• Trail text not bold when it should be #8192
• Parse HTML for Textblockcomponent #7956
• DCR - Parse HTML for blockquote element (No more unwrapping!) #7650

[cemms1]

Suggested solution:

Include sensible defaults after the CSS reset block in our renderers.

There is a resets.defaults in @guardian/source-foundations which we are not currently using, but might be a good idea to use!

Alternatively, we could create a sensible default CSS block specifically for this repo, if we think our requirements are going to be widely different from others in the department (I don't think they will be, but we could always have both).

The resets.defaults CSS in csnx would need adjusting as it currently does not address <strong> tags for example