Tabs not responsive after CSS change

I’m no expert but from my limited experience with this great plugin I think I know your problem.

You need to give the shortcode a class name in the css like this:
.sub-tabs.my-custom-tabs .su-tabs-panes {
width: 934px !important;
}

The important point is that any class has to be added to the type of shortcode first e.g. .sub-tabs
The custom class has to be written with no space between e.g.
.su-tabs.my-custom-tab and NOT .su-tabs .my-custom-tabs

Then you have to attach the class name(exactly as in your css) to your html code on your page e.g.
[su_tabs class=”my-custom-tabs”]
[su_tab title=”Title 1]
Content
[/su_tab]

Hope that works for you.
As I said just a newbie at this but learnt by trial and error about this particular problem.

Kind regards
Kara