In case someone else was looking for a solution - I came up with a quick way to let the sender know something has changed on the page - that appears more obvious.
As Oscar pointed out - there is a section that has the “Email Sent Feedback” message. I changed the colour of that message to green.
Now when someone hits send - the message that your email has been sent is green - and more apparent…
Love the CSS code willow. For some reason, I can move the sent message up higher in the page, and I can change the color of the text, but not the size of the font. Need it to be bigger, but font-size seems to do nothing no matter what numbers I enter. Any help is greatly appreciated! (using Tesla Pro w/ RW6)