You could do something like the following, and just adjust margins and padding to achieve desire effect:
.brownsquare {
background: #colorcode;
padding: 2px;
margin: 2px;
}
.creamsquare {
background: #colorcode;
border: 1px solid #colorcode;
padding: 2px;
}
<img src="image.jpg" class="brownsquare">
<img src="image.jpg" class="creamsquare">