This is how it looks in desktop:

This is how it looks in mobile:

Relevant css:
styles.sass:
item
.row
cursor: pointer
height: 297px
.top-border
border-top: 2px dotted $brand-four
margin: 30px 0 40px
Live site:
(I’m using the Foundation framework).
What could be causing this?
The pixels may be different sizes.
Some browsers also allow magnification of rendered elements to help the visually challenged so the sizes can be different.