Issues formatting Invite to Apply content library notification

Summary:

Having challenges modifying the seeded Invite to Apply content library notification. There a bunch of css code in the notification that I can't seem to decipher. I removed the seeded light blue background, but I still can't get my buttons and text to show as green instead of the seeded blue. Also, I added images, but some are not rendering in the final email. See below screenshots of how it looks when configure in Content Library vs what it actually looks like when emailed.

I've a pasted the html below.

Any help would be greatly appreciated.

Content (please ensure you mask any confidential information):