Check out example codes for "how use befor after for image". It will help you in understanding the concepts better.

Code Example 1

DIV:before {
    content: url(http://name.png);
}

Code Example 2

/* for child  */

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

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