PHP SWITCH STATEMENT: Changing Background Color Base on Day

I created a PHP script using a "Switch Statement" that allow a user to select day from a combobox or a dropdown menu that when a user clicks the submit button, the background color of the page changes depending on what is set. In the following example, I set 

• Monday to color red
• Tuesday to blue
• Wednesday to yellow
• Thursday to green
• Friday to pink
• Saturday to orange and
• Sunday to black

Here is the HTML code:

This one is the PHP script. Copy the code and save it with a .php file extension.