How to make bxSlider work responsively, using old version

How to make bxSlider work responsively, using old version

Hi everyone, 

I am new to this forum and new to bxSlider. I hope I am posting in the right group. 

I have created a carousal slider using bxSlier plugin following an article http://htmldoc.net/2012/11/centered-bxslider-slideshow-with-custom-slide-opacity/. The end result is here  http://alpha.klmnweb.com/sliders I have made some css customization here and there.

It's working find and to what I expected. But the slider is not responsive at all. I tried many css rules still the images do not shrink when I re-size the browser keeping the current layout.

Can I look for some inspiration or suggestion to make this work responsively across all devices. 

Thank you very much in advance and look forward to your support.