Drawing a round shadow on a square element with CSS - css

Question

Is it possible creating a round shadow (a neat circle with the spread value set to zero) under a square element?
E.g. a DIV with no rounded borders.
I have the following element, which I cannot add further markup to:
<div class="square"></div>
In addition, I cannot use :before and :after pseudo-elements, as they are already styled. That's why I am trying to adapt the box-shadow.
In the example below what I would like to achieve (obtained with a ":before" pseudo-element, which I cannot use).
.circle {
width: 20px;height: 20px; margin: 40px 0 0 40px;
display: inline-block; border:1px solid #000;
position: relative; top: 0; left: 0; background: #fff;
}
.circle:before {
content: ''; display: block; position: absolute; top: -15px; left: -15px;
width: 50px; height: 50px; border-radius: 50%; background: #ddd;
z-index: -1;
}
<div class="circle"></div>
I used the :before pseudo-element only to show the result.

Answer 1

I think I found a quite good solution:
.wrapper {
margin-left: 5rem;
margin-top: 5rem;
}
.element {
width: 14px;
height: 14px;
border: 2px solid #5f5f5f;
border-radius: 2px;
background-color: #fff;
}
.element:before {
content: '';
position: absolute;
width: 14px;
height: 14px;
z-index: -1;
border-radius: 50%;
background-color: transparent;
opacity: 0.2;
box-shadow: 0px 0px 0px 13px rgba(0, 0, 0, .6);
}
<div class="wrapper">
<div class="element"></div>
</div>
I hope it will be a helpful answer for you, - Marta.

Answer 2

There are a couple of ways to go about it. I'd simply put the square div in a bigger container div, then style it as you wish. I've included a couple of examples for you.
I hope this helps! - James.
.square {
width: 20px;
height: 20px;
display: block;
position: relative;
background: #fff;
opacity: 1;
margin: 5px 0 0 5px;
}
.circle,.circle-with-spread {
display: block;
background-color: #000;
opacity: 0.3;
width: 30px;
height: 30px;
border-radius: 15px;
position: absolute;
}
.circle-with-spread {
box-shadow: 0 0 5px 5px rgba(0,0,0,1);
}
<!-- Example Circle Shadow -->
<div class="circle">
<div class="square"></div>
</div>
<!-- Spacing makes it look nice -->
<br />
<br />
<br />
<!-- Second Example -->
<div class="circle-with-spread">
<div class="square"></div>
</div>