my div inside a parent container should have a margin of 20px from the top from the container instead the margin top applys to the parent container...
#rules-panel {
 background-color:blue;
 width:80%;
 margin:0 auto;
 height:800px;
}
#rules-panel .box {
 margin:20px;
  margin-top:20px; /* why isn't the margin working */
 background-color:red;
}<div id="rules-panel">
 <div class="box">
  <p>THIS IS div</p>
  <p>THIS IS div</p>
  <p>THIS IS div</p>
  <p>THIS IS div</p>
  <p>THIS IS div</p>
 </div>
  
</div>