How to change the background or text color of the countdown timer to green when there is only 30 minutes remaining to finish the countdown?

******Below is the Code in React JS , in this below code I want to change the background or text color to green when there is only 30 minutes remaining in the countdown timer.

import React, {useState, useEffect} from 'react';

function Counter() {      

    const TimeLeft = () => {
    const countDownDate = new Date("Dec 23, 2020 15:37:25").getTime();
    const now = new Date().getTime();
    let distance = countDownDate - now;
    let timeLeft ={};

    timeLeft  = {
      days: Math.floor(distance / (1000 * 60 * 60 * 24)),
      hours: Math.floor((distance / (1000 * 60 * 60)) % 24),
      minutes: Math.floor((distance / 1000 / 60) % 60),
      seconds: Math.floor((distance/ 1000) % 60)
  }
return timeLeft;
}

const [timeLeft, setTimeLeft] = useState(TimeLeft());

useEffect(() => {
    const timer = setTimeout(() => {
      setTimeLeft(TimeLeft());
    }, 1000);
    
  return () => clearTimeout(timer);
  });
  
  return (
    <div>
      <h1>Hurry</h1>    

      <h3>{timeLeft.days}Days&nbsp;{timeLeft.hours}Hours&nbsp;{timeLeft.minutes}Minutes&nbsp; 
          {timeLeft.seconds}Seconds    </h3>     
     
    </div>
  );
  }
  export default Counter;