React - Modal expands div in footer div not on main screen - reactjs

Question

New to coding, trying to get a modal to work. It is not opening the way I expected it to.
The component is currently loaded within the footer div of my site. And when the button is toggled it simply hides or shows a div within the footer. I want it to appear in the centre of the webpage as a modal.
import React, {useState} from 'react';
import './policy.css'
export default function Policy() {
const [modal, setModal] = useState(false);
const toggleModal = () => {
setModal(!modal);
};
if(modal) {
document.body.classList.add('active-modal')
} else {
document.body.classList.remove('active-modal')
}
return (
<>
<div>
<button onClick={toggleModal} className='btn-modal'>
<p>Privacy Policy</p>
</button>
</div>
{modal && (
<div className="modal">
<div onClick={toggleModal} className="overlay"></div>
<div className="modal-content">
<h2>Privacy Policy</h2>
<p>This is the privacy policy</p>
<button className='close-modal' onClick={toggleModal}>Close</button>
</div>
</div>
)}
</>
);
}

Answer 1

The simplest way to achieve a modal effect is to use some CSS.
You could try a very crude style like (from MUI Modal docs):
const style = {
position: "absolute",
top: "50%",
left: "50%",
transform: "translate(-50%, -50%)",
width: 400,
bgcolor: "lightgrey",
border: "2px solid #000",
boxShadow: 24,
padding: 4,
};
Then apply it to your modal:
<div className="modal" style={style}>