Write the necessary HTML and CSS to create a layout as follows (using HTML5 semantics):
- The two content elements and side element must be next to each other
- These three elements must be vertically aligned
- Total sum of the 3 elements must be 100%
- The footer should have a width of 100% and a height of 200px
- Make the height of the 3 elements be 100% โ the 200px of the footer