display div in center of page css code example

Example 1: center div in middle of page

.centered {
  position: fixed;
  top: 50%;
  left: 50%;
  /* bring your own prefixes */
  transform: translate(-50%, -50%);
}

Example 2: how to center an image element inside a block in css

img { display:block;
      margin-left: auto;
      margin-right:auto;
      }