This is what I have presently:

Here’s my code so far:
<style type="text/css">
.main
{
background:url(bg.jpg);
height:250px;
}
.ban
{
background-color:#333;
height:150px;
}
.mask
{
width:75px;
height:75px;
float:left;
border:#fff solid 1px;
margin:20px;
}
</style>
<div class="main">
<div class="ban">
<div class="mask"></div>
<div class="mask"></div>
<div class="mask"></div>
<div class="mask"></div>
<div class="mask"></div>
</div>
</div>
Here’s what I am aiming for:

I am looking to create a mask using CSS – what do I need for this?
Instead of trying to create the svg or png image to position against, you could use borders (if you’re using a solid color that’s easy to work with) to replicate this.