some of our users have javascript off by default due too company rules...
I would suggest to change tabs.css form display: none to
.tab-content {
display: block;
}
and add the following to the links <a ... of each tab:
href="#choose_an_proper_name"
and set the proper id for each tab - surprise :D
id="#choose_an_proper_name"
if my tests are right this would work for people without js or css (screen readers)
Greetings