Blog Post Preview Image size not correct after upgrade to Enfold 4.0.2

I just updated my Enfold theme to 4.0.2 with WordPress 4.7.3 and an odd thing happens on the Preview Image size on my blog post listings in Firefox….

Even though I have specified that the image size be 180px wide in the dashboard…from the 4th image down in the listing the Blog image size is 450 px wide in Firefox….it appears OK in chrome and safari

Here is the page with the post image size issues see 4th & 5 th post compared to first 3 posts

Here is the site before the upgrade to Enfold 4.0.2 and it appears OK in Firefox–
http://uvpublichealth.org/news/

No settings were changed.

It appears that the styling–

.small-preview img, .big-preview img {
width: 100%;
}

is making the image larger? is that correct.

If I change this to

.small-preview img, .big-preview img {
width: 180px;
}

it seems to fix the Firefox issue … but then on my iphone the image is too small and does not fit the 100% width intended for the mobile device

If I made the above change….or do you have another suggestion…what is the Media Query I need for mobile devices.

Any thoughts on why the upgrade is causing problems?