<div>
<span data-media="(min-width: 240px) and (max-width: 480px)" data-src="http://example.com/.../slide_480x120/.../pic.png" width="480" height="120">
</span>
<span></span>
<span></span>
<span></span>
<img src="http://example.com/.../slide_480x120/.../pic.png" width="480" height="120">
</div>
<div>
<span data-media="(min-width: 240px) and (max-width: 480px)" data-src="http://example.com/.../slide_480x120/.../pic.png" width="480" height="120"> </span>
<span data-media="...and (min-device-pixel-ratio: 2), ...and (-o-min-device-pixel-ratio: 2), ...and (-webkit-min-device-pixel-ratio: 2), ...and (min-resolution: 2dppx)"
data-src="http://example.com/.../slide_960x240/.../pic.png" width="480" height="120"> </span>
<span></span> <span></span> <img src="http://example.com/.../slide_480x120/.../pic.png" width="480" height="120">
</div>