Explanation.
Structure (HTML):
The code starts with the basic structure of an HTML document.
It defines the document type (DOCTYPE), language (lang=”en”), and title (<title>Calculator</title>).
The body section contains the main content of the calculator.
Inside the body, a div with a class container holds another div with a class box. This creates a container for the calculator layout.
Within the box div, a <form> element captures user input and handles button clicks.