css margin-top not working code example

Example 1: css margin bottom

.yourClass {
  margin-bottom: 25px;
}

Example 2: css margin top

.yourClass {
  margin-top: 25px;
}

Example 3: margin-top not working

.form_head {
    margin-top: 20px;
    color:#58585a;
    font-size:22px;  
    display:block; /* Add this */ 
}