How to make widgets responsive

Hi there. I just installed Widgetize Pages Light, and I love it! I’m running it on a test page before I use it for my home page. You can find it at http://thefinancegirl.com/test.

I am wondering how to make this widget work with my responsive theme. If you load this test page on a mobile device, the grid is really small compared to the rest of my site, which runs on a responsive theme (Modern Blogger Pro via Studiopress).I would like the images to get larger so each is as wide as the screen when it’s resized or on a mobile device. Please let me know how I can achieve this.

Thanks so much!

https://ww.wp.xz.cn/plugins/widgetize-pages-light/