Could I ask you to point me in the right direction how can I match these two buttons like in the demo - screenshot of the demo and my website attached. 

Thank you, Judith

Thank you for your prompt reply. It's already set like that, please see the screenshot of my settings. But the button on the left gets that style, however, on the rights not, do not know why.  

I added the CSS to the shop page, but the design is still the same

Thank you