Header

Left Section

This column should be 50% width when less than 800pxl

This column should be 100% width with less than 400px. It should be below the Center section.

Center Section

This column should be 50% width when less than 800px.

This column should be 100% width when less than 400px. It should be on top.

Right Section

This column should be below Left & Center when less than 800px. It should be 100%

Remove This column at less than 400px;