Close #961: Add hover effect to buttons on website

[jamesnottidge]

Related issue

Closes #961

Context / Background

Previously, hovering on a button provided no change in the ui.

I believe this little bit of visual feedback would make users aware the button is clickable and encourage them to interact with it.

What change is being introduced by this PR?

I added a hover effect to the buttons, making each button just a bit darker on hover.

How will this be tested?

Hovering on a button should provide visual feedback

P.S I am a beginner at open source who would gladly accept any and all feedback.

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[araujoarthur0]

@jamesnottidge can you please add images to the PR with a before/after?

[jamesnottidge]

done

[tupaschoal]

\changelog-update Message: Enhancement [#961]: Add hover effect to buttons on website