Say I have container.a and it has some height in pixels, say I have another container.b within container.a that is 80% of container.a, now say I want to fit an image that has some height in pixels into container.b, how can I make the image be the height of container.b, and then maintain the width aspect ratio using CSS?
<div class="container.a">
<div class="container.b">
<img class="image.a" src="my_image.png" />
</div>
</div>
.container.a { width: 200px; height: 300px; }
.container.b { width: 80%; height: 80%; }
.image.a { ? }