Absolutely no javascript/jQuery or any other progamming language, just CSS.
Also no inputs, radio, checkbox, summary/detail etc. Just focus and focus-within.

This is a simple tree menu that works with any number of branches and links without any change to the CSS.

It also uses the old method of animating max-height to give a slide action to open each branch. There are newer and better methods of animating from 0 to auto height, but this method works on older browser versions.

Click/tap the hamburger icon at the top left of the screen to open the first level.

Click/tap the bold text with pointer to open that branch, and also to close that branch including any open sub branches.

To close the menu you can click/tap the cross or click tap anywhere off the menu. This will also close any open sub branches.

The snowboarder animates on page entry using just CSS @starting-style which has been available on all browsers since mid 2024.