I really want to emphasize a button on a Page Layout by using the brand feature. As in the examples in the Link below. I am used to web development where I use Chrome's inspect feature top identify a class and/or id and use CSS to stylize it. It is apparent, however, that Salesforce works very differently, and I have no idea how. I am merely trying to add CSS to ONE button on my page layout (in the highlights panel). Could anybody direct me to the best way to do this? I am starting at square one, so any advice would be appreciated. Is this something I need to create a full lightning component for? Or could I tackle this using a static resource. Please advise!

https://developer.salesforce.com/docs/component-library/bundle/lightning:button/documentation

I am trying to get a Toast success message to display once a flow is completed. I built out the lightning component bundle here: http://www.thecloudfountain.com/salesforce-lightning-forceshowtoast/ and now want the message to display upon flow completion