body {  margin: 0;
            font-family: arial;
            background: white;
            overflow-y: scroll;
            width: 100%;
            }

.header { top: 0; width: 100%; display: inline-block; text-align: left;  margin: 0px;  background: blue; color: white; height: 80px; }

.main_div { display: inline-block; text-align: center; width: 100%; background: lightgray; }

.cnt_center { display: inline-block; float: left; text-align: center; width: 100%; margin-left: 210px; margin-right: 210px; background: lightgreen; min-height: 600px; } 

.cnt_left { display: inline-block; text-align: center; background: gray; min-height: 600px; float: left; width: 200px; } 

.cnt_right { display: inline-block; text-align: center; background: gray; min-height: 600px; float: left; width: 200px; } 

.footer {
  width: 100%;
  background-color: red;
  color: white;
  text-align: center;
  height: 60px;
}