Login forms on https site

The client added a security certificate to the site and there is a redirect in the htaccess file to change all http to https. None of the Login pages work now. I have searched the forum but didn't find what I needed to make it work. These forms have been working for several years so I'm sure it has something to do with the security certificate. When you enter the user name and password and hit submit it says this is a non secure form and nothing happens users are not logged in. I am attaching the two log in pages. Can you assist? Thanks.
site is https://preferred-cell-systems.com

It looks like some of the images and script references on the page are using http:// instead of https://. That might be causing the form to fail.

You may also try changing this line in the htaccess:
RewriteRule ^(.*)$ https://preferred-cell-systems.com/$1 [R,L]

to:
RewriteRule ^(.*)$ https://preferred-cell-systems.com/$1 [R,P]

Ray, THANKS for your help. This fixed the problems and all appears to work as it did in the past. It's not a lot but check your donation, you deserved much more but....times are tough eh? Thanks again.

Thanks, I'm glad it worked.