reduce size in reponsive css code example

Example 1: Scaling Images and Videos css

.container {
  width: 50%;
  height: 200px;
  overflow: hidden;
}

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

Example 2: how to set background image in css responsive

body{
  background:url("images/xyz.jpg") no-repeat center;