Svelte: Change classes of checked checkbox (without creating variable for checkbox)

I am kind of new to Svelte and trying to solve this (seemingly trivial) problem with my UI:

I would like to change the classes of a checkbox and/or its parent element when the checkbox is checked. The Svelte docs tell me to create a boolean var for every checkbox and bind activation the classes to it: https://svelte.dev/tutorial/class-shorthand

but I have a random amount of checkboxes and many different types of checkboxes with different behaviour in styling and I don't want to create (or generate) a variable for every single checkbox.

Is there any elegant way in Svelte for changing the classes of checkboxes when they are indivually checked? (vanilla javascript instead if jquery if possible :) )

Cheers Some Svelte noob