You probably heard Poland implemented Sunday shopping ban?
If you're based in Poland or plan to visit us, I'm sure my calendar will help you (red Sundays=most shops are closed). 

Codepen: 
- current version: https://codepen.io/ElaMoscicka/pen/bxdgYR  
- version with selecting months using search bar: https://codepen.io/ElaMoscicka/pen/eraeGM
- version with dropdown menu: https://codepen.io/ElaMoscicka/pen/NMOvLg
- 1st version: https://codepen.io/ElaMoscicka/pen/xjxYmy)

Inspiration: https://www.w3schools.com/howto/howto_css_calendar.asp