Awesome contribution @Dana!! If I could add 1 small enhancement idea, in order to give it a more quickbase feel:
var text CB= URLEncode([Activity Details]);
var text Alert= URLEncode("Activity Details" & " were Copied to the Clipboard");
"<a class='Vibrant Success' style=\"border:0px solid green; background-color:green; text-align: center;\"href=" &
"javascript:{" &
"navigator.clipboard.writeText('" & $CB & "').then(function(){" &
"},function(){" &
"});" &
//"alert('" & $Alert & "');" &
"$.jGrowl('" & $Alert & "');" &
"};" &
">Copy to the Clipboard</a>"
Replacing your "alert" with "$.jgrowl" will throw the native QB growl message which is a little prettier than a javascript alert. FYI to everyone else -- this will work for any situation where you are using alerts in this fashion.