Responsive Product Lable Images

Responsive Product Lable Images

We upload images at category and product detail pages. 
However we cant seem to resize these so they show appropriately in Mobile vrs Desctop. 

Eg:
Category: 
Desktop 


Then in mobile, this is tiny eg:


Like wise on Product Detail Pages. 
Desktop


Mobile PDP is tiny. 


How should the sizing or advanced CSS be handled to correctly achieve a viewable size for both?

Thanks in advance to anyone with advice for this.