I'm sorry to add to the many other asks on this subject, but I've spent the best part of 2 hours following other recommendations in threads to no avail.
My site is: http://soloscribe.co.uk
Running vers - 3.4
Pages I wish to change background colour of widgets are "Pricing" and "Contact Us" where the contact forms appear.
Plugin for forms: Custom Contact Form by Taylor Lovett
Also using Dynamic Widgets plugin
My theme has a base.css for most styling. I have tried in here, as well as the sidebar.php file and .css for the Custom Contact Form plugin. I do the usual 'inspect element' to find the path in Chrome.
I know how to change color for all widgets, but really want to style these forms a little better for aesthetic purposes - hence using individual colors. I also need to increase the border radius on these individual widgets very slightly.
If anyone can offer suggestions as to where I should look, I would be most grateful.