Images in multiple sizes

<img src="imagefile-large.jpg" srcset="imagefile-small.jpg 480w, imagefile-large.jpg 1080w" sizes="50vw">
<img src="mdn-logo-sm.png" alt="MDN" srcset="mdn-logo-HD.png 2x">
<img src="clock-demo-thumb-200.png"
      alt="Clock"
      srcset="clock-demo-thumb-200.png 200w,
          clock-demo-thumb-400.png 400w"
      sizes="(max-width: 600px) 200px, 50vw">