我想将显示的文本颜色更改为白色，但是我不知道该怎么做，有人可以帮助我吗？

代码：

<!-- Display the countdown timer in an element -->
<p id="demo"></p>

<script>
// Set the date we're counting down to
var countDownDate = new Date("Sep 22, 2017 15:37:25").getTime();

// Update the count down every 1 second
var x = setInterval(function() {

  // Get todays date and time
  var now = new Date().getTime();

  // Find the distance between now an the count down date
  var distance = countDownDate - now;

  // Time calculations for days, hours, minutes and seconds
  var days = Math.floor(distance / (1000 * 60 * 60 * 24));
  var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
  var seconds = Math.floor((distance % (1000 * 60)) / 1000);

  // Display the result in the element with id="demo"
  document.getElementById("demo").innerHTML = days + "Days " + hours + "Hours "
  + minutes + "Minutes " + seconds + "Seconds ";

  // If the count down is finished, write some text 
  if (distance < 0) {
    clearInterval(x);
    document.getElementById("demo").innerHTML = "EXPIRED";
  }
}, 1000);
</script>

PS 我是菜鸟，此代码来自 W3。