Change Header style – accordion/mobile view

Hi
I am trying to put a background image and color into the different headings for when it shrinks into an accordion view. Ideally i would a different image for the different active heading open.

Trying in the lines of something like below without success. If someone could share a light on this please

.responsive-tabs .responsive-tabs__heading #tablist1-panel1 {
background-image: url (‘http://www.website.com/wp-content/uploads/2014/04/sverige-repeat.png’)!important;
background-repeat: repeat-x!important;
}

Thanks

https://wordpress.org/plugins/tabby-responsive-tabs/