"Close” button inside the “Subscribe to Firefox Monitor” dialog does not have the correct hover state

[obotisan]

[Affected versions]:

• Firefox 62.0
• Firefox 64.0a1

[Affected Platforms]:

• Windows 10 x64
• macOS 10.13
• Ubuntu 16.04 x64

[Steps to reproduce]:

1. Navigate to https://fx-breach-alerts.herokuapp.com/
2. Click on the Subscribe button.
3. Hover with the cursor over the "Close" button.

[Expected result]:

• The "Close" button is highlighted with a darker blue color.

[Actual result]:

• The "Close" button is highlighted with a light grey color.

[Regression]:

• I don't think this is a regression.

[Notes]:
Please look at the image:

[lesleyjanenorton]

Fixed in #378

[CiprianGeorgiu]

HI @lesleyjanenorton, I have verified this issue on herokuapp and now the "Close" button gets underlined when hovering over it. I just want to make sure that this is the right behavior since looking at the visual specs I can see a different hover state?