react Js, css3

Hi Jyotirmoy,

Good attempt. I can see you've got the logic down however there are some serious issues with the UI, UX and accessibility:

• The previous operands overlap the current/evaluated operand in the parent container when you have a digit value entered which extends the width
• When a new operation is entered, this isn't appended to the end of the previous operand, it replaces the operation previously entered (e.g. 1 + 2 - 3 ends up becoming 1-23)
• Your theme also switches suddenly in responsive view (ie. when I choose theme two, it goes back to theme one at a min-width of 440px whilst keeping the switch position the same)
• It would be good to have the ability to enter in values and operations using the keypad on a keyboard
• Your design fails accessibility standards for background/foreground contrast ratios
• The buttons also don't have an accessible name for assistive technologies and screen readers

I'd suggest maybe sticking to the original style guide to start with until you have more experience with UI design.

Also, avoid using Create React App for any React applications moving forward. Meta no longer supports this and it's recommended in this instance to switch to Vite.

Hope this helps!