Images Larger than Container
This will center the image inside of a element when the elements height and/or width is smaller than the image. This works well when you have image assets of various aspect ratios that you want to display as thumbs that are the same size.
Sandbox Demo
HTML
<ul class="thumbnails">
<li>
<img src="https://via.placeholder.com/400x300/9932CC/FFFFFF">
</li>
<li>
<img src="https://via.placeholder.com/500x300/7FFFD4/000000">
</li>
<li>
<img src="https://via.placeholder.com/300x200/87CEFA/000000">
</li>
<li>
<img src="https://via.placeholder.com/300x400/F4A460/000000">
</li>
</ul>
CSS
ul.thumbnails {
display: flex;
flex-wrap: wrap;
}
ul.thumbnails li {
height: 150px;
border: 4px solid #FFF;
overflow: hidden;
position: relative;
width: 150px;
}
ul.thumbnails li img {
position: absolute;
top: -9999px;
bottom: -9999px;
left: -9999px;
right: -9999px;
margin: auto;
width: 250px;
}