Plugin directory download button horizontal padding

[stephdau]

I've noticed that the lack of horizontal padding on the plugin download button leads to display issues with long version numbers: ​https://cloudup.com/i7ZJ4f763mi

There is a min-width value on the button itself, but the long string pushes itself to the very edges, in some cases.

I've found that adding horizontal padding (12px in patch) to the button seems to have the desired design intent:

• ​https://cloudup.com/iiH_R4YTwlU
• ​https://cloudup.com/id4sktWJPaS

The same padding could also be added to the link within instead, but that'd be 1 extra line of CSS, vs just 4 characters by modifying the link's styles.

[stephdau]

Example taken from ​https://wordpress.org/plugins/nextgen-gallery/

[Otto42]

Looks good. Added.