Style Gutenberg buttons

[grarighe]

Today I've added/edited these pages on the handbook and I used some Gutenberg buttons as CTA:

• https://handbook.hmn.md/the-company/branding/
• https://handbook.hmn.md/the-company/branding/human-made/
• https://handbook.hmn.md/the-company/branding/altis/

I noticed that the button label is not visible on mobile (Chrome / Galaxy S8)? @mattheu said they're not visible on desktop either? OR maybe do they show up red on red? not sure.

Those pages are public, so it would be nice to fix those buttons and their hover effect too, that it's currently pushing down the rest of the page.

[grarighe]

Adding a screenshot:

[richardswain]

Buttons have been replace with links. Current screenshot:
(Can confirm the Gutenberg buttons still have the above text colour / jumping issue if used).
Issue can be closed if text is adequate.

[richardswain]

I have styled these buttons up locally, using hm-red-dark for hover and focus, seen on the Altis button. (I don't know what the original hover effect was, if any.) Aligned the buttons and removed the border bottom which caused the jumping. Do we want this or use the current text? @mattheu ?