Update all Buttons Styles

[cjeria]

@alextsg I went through the entire app and compiled all screens that use old buttons styles. Let's update those to these styles

Style guide w/specs

I created a codepen with active styles in CSS:
https://codepen.io/cjeria/pen/RQvKqq?q=flat%20button&order=popularity&depth=everything&show_forks=false

Screens where buttons need to be updated:

[cjeria]

The signature screen buttons also need to be updated. Let's use our standard blue for the main positive action button.

Also, this sign request pop up also needs a slight refresh to match the new UI styles. I'll create a new ticket for this task.

[cjeria]

issue for updating sign popup styles #3578

[danfinlay]

@cjeria is the design complete on this? If so, could you update the pipeline to Development Ready?

[cjeria]

@danfinlay cool, yea this one's ready for dev. Should the pipeline pending development?

[danfinlay]

Yeah that's right. Sorry been playing with pipeline names.