how to change mic background color in react code example

Example: React microphone

import React, { useState, useEffect } from 'react';
// the button form material-ui is optional
// npm install @material-ui/core
import Button from '@material-ui/core/Button';

const SpeechRecognition =
  window.SpeechRecognition || window.webkitSpeechRecognition
const mic = new SpeechRecognition()

mic.continuous = true
mic.interimResults = true
mic.lang = 'en-US'

const RecordButton = () => {

    const [isMicOn, setIsMicOn] = useState(false);

    var buttonColour;
    var buttonLabel;

    if (isMicOn) {
        buttonColour = "secondary";
        buttonLabel = "Recording...";
    } else {
        buttonColour = "primary";
        buttonLabel = "Record";
    }

    useEffect(() => {
        handleListen()
      }, [isMicOn])
    
    const handleListen = () => {
    if (isMicOn) {
        mic.start()
        mic.onend = () => {
        console.log('continue..')
        mic.start()
        }
    } else {
        mic.stop()
        mic.onend = () => {
        console.log('Stopped Mic on Click')
        }
    }
    mic.onstart = () => {
        console.log('Mics on')
    }
    
    mic.onresult = event => {
        const transcript = Array.from(event.results)
        .map(result => result[0])
        .map(result => result.transcript)
        .join('')
        console.log(transcript)
        mic.onerror = event => {
        console.log(event.error)
          }
        }
      }
	// if you don't want to us the button from Material-ui, just change Button to button
    return(
        <Button variant="contained" color={buttonColour} onClick={() => {setIsMicOn(!isMicOn)}} >{buttonLabel}</Button>
    )
}

export default RecordButton;