CSS variables, CSS grid, Javascript

Hi Vinícius!

Nice work! That's a very nice solution and handling gracefully those operations. I'll answer your question and give some feedback on what I observed (please note there are other ways to address this theme switcher):

• I would choose a radio input instead of a range input. To me it would make more sense to provide the user with a "1 choice out of 3" (which is what you did too!) but this is what radio buttons are for. It would be easier to deal with also because you can retrieve the value from the built-in element. With this, you might be able to get rid of the switch and directly assign the value to the body as a class.
• You could be a little more consistent with the onchange event you added on the html and use addEventListener like you did everywhere else.
• I think you can take your addEventListener outside each function the wrapping functions don't serve a purpose (such as execOperations, clear, ...).
• to maintain consistency and standards, pick one type of casing. In certain places you have a blend of camelCase and snake_case (clearAll_button), and in other places you use either or. In frontend the standard is camelCase.
• Seems like you know how to code - not sure of your background - but depending on the task, vanilla Js (UI projects) are event driven, which mean that functions are probably tied to an event up the chain, and not often ran on their own (like your clear and execOperations do). This calculator is good project to make it only event driven with helper functions like your calcAdd, calcSub, ... . Now this is just feedback for this project, you'll find vanilla Js/Node projects that do not qualify to be mainly event driven.

Great work! Hope this helps