Bootstrap also comes with some useful built-in image modifiers, namely, rounded, img-thumbnail, and rounded-circle. Let's apply these to the images in our example:

<div class="container">
    <h1>Our Print Sizes</h1>
    <div class="row">
        <div class="col-sm-3">
            <img src="images/small.jpg" class="img-fluid rounded-
            circle">
            <h5>Small</h5>
            ...
        </div>
        <div class="col-sm-3">
            <img src="images/medium.jpg" class="img-fluid rounded">
            <h5>Medium</h5>
            ...
        </div>
        <div class="col-sm-3">
            <img src="images/large.jpg" class="img-thumbnail">
            <h5>Large</h5>
            ...
        </div>
        <div class="col-sm-3 ">
            <img src="images/extra-large.jpg" class="img-fluid">
            <h5>Extra Large</h5>
            ...
        </div>
    </div>
</div>

Take a look at Figure 2.16:

You may note that in the previously mentioned code, for the Small and Medium images, we have kept img-fluid but removed img-fluid from Large. This is because an img-thumbnail actually uses img-fluid as a mixin, while rounded-circle and rounded pay zero respect to the parent column width, so the img-fluid class is necessary. These images nicely scale down to xs displays, but it does look a little cluttered on a small viewport. Consider Figure 2.17:

Apart from the rounded-circle and rounded classes, Bootstrap also offers classes for rounding per side: up, down, left, or right. For example, the rounded-top class rounded the top corners of an element. Similarly, the rounded-bottom class would round the element’s bottom corners by setting the border-bottom-right-radius and border-bottom-left-radius properties to 0.25 rem.

Let's apply the classes with the following in mind:

• The image for the Small category has its right corners rounded
• The image for the Medium category has its left corners rounded
• The image for the Large category has its bottom corners rounded

Observe the following code:

<div class="container">
    <h1>Our Print Sizes</h1>
    <div class="row">
        <div class="col-sm-3">
            <img src="images/small.jpg" class="img-fluid rounded-  
            right">
            <h5>Small</h5>
            ...
        </div>
        <div class="col-sm-3">
            <img src="images/medium.jpg" class="img-fluid rounded-       
            left">
            <h5>Medium</h5>
            ...
        </div>
        <div class="col-sm-3">
            <img src="images/large.jpg" class="img-fluid rounded-    
            bottom">
            <h5>Large</h5>
            ...
        </div>
        <div class="col-sm-3">
            <img src="images/extra-large.jpg" class="img-fluid">
            <h5>Extra Large</h5>
            ...
        </div>
    </div>
</div>