css img responsive size code example

Example 1: responsive img

.responsive-img {
  max-width:100%;
  display:block;
  height:auto;
}

Example 2: responsive image using media query

.img {
  background-image: url(examples/images/image-384.jpg);
  background-image: 
    -webkit-image-set(
      url(examples/images/image-384.jpg) 1x,
      url(examples/images/image-768.jpg) 2x,
    );
  background-image: 
    image-set(
      url(examples/images/image-384.jpg) 1x,
      url(examples/images/image-768.jpg) 2x,
    );
}