Sensei: Hover styles for buttons are inconsistent

[alexsanford]

On a course page, the hover styles for the buttons "Start Taking This Course" and "Contact Course Teacher" are inconsistent:

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cc @pgk

[donnapep]

This appears to be a theme conflict (likely with the Storefront theme?), as the hover styles are the same when using the Twenty Fifteen / Sixteen / Seventeen themes. (Tip: It's helpful to include the theme as part of the issue description, just in case. :)

[alexsanford]

@donnapep Yes, I was using the Storefront theme when I found the issue. And I can confirm that it does not appear to be a problem on the Twenty Seventeen theme.

Thanks for the tip! I will remember that next time 😄