TODO

• Add Prettier and ESLint. ✅
• Screen: ✅
  • Display numbers entered. ✅
  • Accept combinations like 001, 100111 and 22378008. ✅
• Operations: ✅
  • + or - should result in the number being pushed to a 'mathematical stack' [MS is presumably a pair of numbers - aggregate and next number], and then another number can be added. ✅
  • AC clears the stack & screen. ✅
  • Clicking the = would then add/subtract the number with the previous number in the stack. ✅
  • Using the = will trigger the - or + of the previous numbers in the stack, and push the answer into the stack and show it on the screen. ✅
• Then: ✅
  • Layout. ✅
  • Shared colors - numbers, operations, equals. ✅
  • Styles - once over on current layout: ✅
    • Cursor. ✅
    • Proper buttons. ✅
    • Prevent selection of button text. ✅
    • Separate calculator border / background. ✅
    • Center and resize text. ✅
    • Buttons perhaps square, no padding, hover / active colors. ✅
    • Contrasting color for equals. ✅
    • Font pairing (header + buttons). ✅
    • Colors - background gradient to match equals? ✅
  • Help widget, or title text on buttons? ✅
  • 🥚 ✅
  • Change links to buttons. ✅
  • Keyboard keys for all (0-9 + - =, and AC/CE can be 'backspace'). ✅