Change CSS according to Date

Hello! I am making a WordPress theme that will change its colors and graphics according to the date. For example, if it is December 25th, Christmas, it will change to Christmas colors and Christmas graphics.

So, I figured I can change the CSS file according to the date. However, I don’t want to manually change it, I would like PHP or something to change it for me. How can I achieve this?

For example, PHP realizes its December 25th and adds a stylesheet link to css/christmas.css. Then on December 26th it removes it so it uses the default css. Thank you very much, I highly appreciate it.