My default styles for images…
<style>
img {
display: block;
width: 100%;
height: auto;
margin: auto;
}
</style>
The HTML part…
<picture>
<source media="(min-width: 1025px)" srcset="image-1260px.jpg">
<source media="(min-width: 769px) and (max-width: 1024px)" srcset="image-1024px.jpg">
<source media="(min-width: 481px) and (max-width: 768px)" srcset="image-768px.jpg">
<source media="(max-width: 480px)" srcset="image-480px.jpg">
<img src="image-1260px.jpg">
</picture>