Added Back Button

[vaibhavi-roy]

I have added styling and functionality of back button.

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[DhanushNehru]

Please resolve the conflicts by pulling & merging the updated code

[DhanushNehru]

Please check out the merge conflicts

[vaibhavi-roy]

@ppfeiler @DhanushNehru I have done the necessary changes. Please check them out Thank you

[DhanushNehru]

@vaibhavi-roy the whole UI is improper

https://deploy-preview-12--calculator-dhanushnehru.netlify.app/

[vaibhavi-roy]

https://user-images.githubusercontent.com/97877161/194005709-b96d2f33-d271-42ea-808c-da323235805a.mp4

@DhanushNehru Everything is working fine at my side. I am unable to understand what's the problem here.

[DhanushNehru]

Pull the latest code & Please resolve all the merge conflicts @vaibhavi-roy

[vaibhavi-roy]

@DhanushNehru Please check out once. I have done the changes.

[DhanushNehru]

I am still facing the same @vaibhavi-roy

https://deploy-preview-12--calculator-dhanushnehru.netlify.app/

Possible to close this PR , merge the existing updated code & raise another one with proper changes