Tip calculator app - HTML + CSS + JS

It took a lot of time but I finally managed to make it work. But my logic is still flawed, I can't seem to be able to gather the value of the selected button without a click... So the app works perfectly fine (almost...), but the UX is not very good in the end. Maybe use checkboxes for the tip percentage values? I don't know... It would have been a lot easier with a "calculate now" button, but hey! that's the fun of it! Great exercice, anyway, really enjoyed it