In e-mails, button format appears differently in certain versions of web outlook - how to fix?

[char-siuu-bao]

In e-mails sent from Nationbuilder, the button formatting appears normally when sent to gmail accounts, but spans the entire width of the e-mail in some versions of Outlook webmail.

What it looks like in gmail (and what it's supposed to look like):

What it looks like in Outlook webmail (not very good!):

[JosephMcArthur]

epic stumbling reveals this

• https://gist.github.com/liamget/c3a27429458e136c00a5658caed42f95
• https://litmus.com/blog/a-guide-to-bulletproof-buttons-in-email-design