Add
overflow: auto;
to the CSS.
So, CSS Class would look like...
.mainDivCenter {
overflow: auto;
width:1250px;
margin:0 auto;
padding-top:5px;
padding-bottom:5px;
background-color:#FFD47B;
border:1px dotted gray;
border-radius:20px 20px;
padding-left:30px;
padding-right:30px;
min-height:680px;
height:100%;
}