pseudo element image content code example

Example 1: html img pseudo class

Doesn't work. Only containing tags can have psuedo class children.

e.g. <div>, <p>, <span>, etc...

Example 2: how use befor after for image

/* for child  */

.custom_img:after {
    content: "";
    background-color: #2359cf;
    height: 400px;
    width: 70%;
    top: -15px;
    right: -6px;
    position: absolute;
    z-index: 999;
}