That image only contains 200 pixels horizontally, but the browser stretches it to 400px wide or even farther!Luckily, you’ll see there’s an easy “fix” there at the end: our old good friend the width attribute!<img src="example.gif", srcset="example.gif 200w" sizes="(min-width: 400px) 400px, 100vw" width="200" /* <=== TA-DA! */ class="logo">As long as you can specify the width attribute so it reflects the true maximum size of your largest image, you won’t run into this problem of having sizes make your image wider than it naturally should go.

The selected source size affects the intrinsic size of the image (the image’s display size if no CSS styling is applied).

Of course in the world of responsive images, we put constraints on our images with CSS:img { max-width: 100%;}Now the image appears at it’s natural size unless it’s constrained by the parent container! Excellent.