Adding drop shadow to Summary block images in List layout

I'm trying to add drop shadows to images in a Summary block. I did it no problem on the  Public Reports page using the Grid layout. But when I try it with a List layout on this testing page stuff goes wonky. Here's what I have in the page header code injection:

<style>
.sqs-block-summary-v2 .img-wrapper {
  -moz-box-shadow:    0px -2px 15px 0px rgba(0,0,0,0.2);
  -webkit-box-shadow: 0px -2px 15px 0px rgba(0,0,0,0.2);
  box-shadow:         0px -2px 15px 0px rgba(0,0,0,0.2);
}

.sqs-block-summary-v2 .summary-item {
 overflow: visible;
}
</style>

Screenshots of what the page looks like before and after I added the overflow:visible bit are attached:

* Before, the drop shadow is not visible on the top and left of the images.
* After, the drop shadows are visible, but the layout goes very wonky.

Any suggestions?

Can you share link to the error page?