Error: Migrate CSS to Tailwind

[wei2912]

This PR removes assets/css/ghost/errors.css and replaces the classes with somewhat equivalent CSS styles.

Tbh I haven't tested the theme error stack as I have no idea how to trigger that error.

[partysnax]

You can view the error message by triggering error 404, such as visiting any page that doesn't exist on your local instance eg. localhost:2368/abcd/

The original error screen for reference:

I feel that to best match the original design in error.hbs :

• In line 3 under the section tag, the classes content-center can be removed (redundant) and prose should be removed (adds unnecessary margins between each line of text)
• Line 4: Give the statusCode the class text-6xl
• Line 5: Give the message the classes text-gray-400 text-xl

These are just suggestions, feel free to fine tune them

[wei2912]

@partysnax Thanks for the review! I was looking to use prose to standardise the formatting across all pages, but I think it would require some special set up to prevent the h1 styles from being overridden. Been looking into that since 2 weeks ago...