Mobile view

Hi there,

I am very new and not experienced in the least with building websites. I have started an e commerce store using wordpress and thought i chose a theme that would work well on a computer as well as a mobile device. I am using My Store By Kaira as my theme. However when I minimize my computer screen or look at my site from a mobile device my calculate shipping options in the shopping cart are almost if not completely gone. How do I fix this issue, so customers can shop from their phone?
Do I need to add a plug-in or is their a simple adjusmtent to make?
Thank you for your time