update npm packages

Edited the readme file to add detail about the project and a screenshot image

added strict equality to some conditionals.

Added rel noopener noreferrer to the github anchor.

made the buttons cursor to pointer & button outline to none.

Added an h3 which says the style is like the iphone's calc app.

Added my github link.

shown a horizontal scrollbar when the calculations text is too big.

Limit calculation results to show only 12 digits.

restrict number input to less than or equal to 12.

changed background colors of the buttons & font sizes.

handled devide by zero with an error message.

Fix: don't add sign when result is empty.

Changed some styling.

Made zeros to not repeat at the beginning.