var root = document.documentElement;
let vh = window.innerHeight * 0.01;
root.style.setProperty('--vh', `${vh}px`);

// We listen to the resize event
window.addEventListener('resize', () => {
  // We execute the same script as before
      let vh = window.innerHeight * 0.01;
      root.style.setProperty('--vh', `${vh}px`);
});

function timeDifference(current, previous) {

  var msPerMinute = 60 * 1000;
  var msPerHour = msPerMinute * 60;
  var msPerDay = msPerHour * 24;
  var msPerMonth = msPerDay * 30;
  var msPerYear = msPerDay * 365;

  var elapsed = current - previous;

  if (elapsed < msPerMinute) {
       return Math.round(elapsed/1000) + ' seconds ago';   
  }

  else if (elapsed < msPerHour) {
       return Math.round(elapsed/msPerMinute) + ' minutes ago';   
  }

  else if (elapsed < msPerDay ) {
       return Math.round(elapsed/msPerHour ) + ' hours ago';   
  }

  else if (elapsed < msPerMonth) {
      return 'approximately ' + Math.round(elapsed/msPerDay) + ' days ago';   
  }

  else if (elapsed < msPerYear) {
      return 'approximately ' + Math.round(elapsed/msPerMonth) + ' months ago';   
  }

  else {
      return 'approximately ' + Math.round(elapsed/msPerYear ) + ' years ago';   
  }
}