In the following example, I use checkbox for making a pure CSS dropdown navigation, also available in this jsFiddle example.
Open that fiddle, click
No need for JS or CSS, just add autocomplete="off" to the checkbox. This will prevent the browser from caching the 'checked' status.
Example: https://jsfiddle.net/6g5u8wkb/
Also, if you have multiple checkboxes, I beleive you can add autocomplete="off" to the form element to apply the effect to all inputs fields.