css after and before property code example

Example 1: 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;
}

Example 2: :before css

h2:before { 
    content: "Read: ";
<span class="Apple-converted-space">    color: #F00;</span>
}