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                <div class="eyes">
  <div class="eye"><div class="pupil"></div></div>
  <div class="eye"><div class="pupil"></div></div>


  color: white;
  height: 100vh;
  background: black;
  display: flex;
  align-items: center;
  justify-content: center;

/*Container that contains both eyes*/
  display: grid;
  grid-template-columns: 250px 250px;
  column-gap: 50px;
  row-gap: 15px;
  transition: 200ms;

/*Styling for an eye*/
  width: 200px;
  height: 200px;
  background: white;
  display: flex;
  justify-content: center;
  align-items: center;
  border-radius: 50%;
  overflow: hidden;

  width: 100px;
  height: 100px;
  background: red;
  margin-left: 0;
  margin-top: 0;
  border-radius: 50%;


                //Define vars
var pupilLeft;
var pupilTop;

//Get the eyewidth (parent div of the pupils)
var eyeWidth = document.getElementsByClassName("eye")[0].offsetWidth;
var eyeHeight = document.getElementsByClassName("eye")[0].offsetHeight;

//Get the pupils
var pupil1 = document.getElementsByClassName("pupil")[0];
var pupil2 = document.getElementsByClassName("pupil")[1];
var pupils = [pupil1, pupil2];
//Get the pupils width and height
var pupilWidth = document.getElementsByClassName("pupil")[0].offsetWidth;
var pupilHeight = document.getElementsByClassName("pupil")[0].offsetHeight;

//On mousemove execute MoveEyes
document.addEventListener("mousemove", MoveEyes);

//Make pupils follow the cursor
function MoveEyes(event){
  //Get mouse positions
  var mouseX = (event.clientX / window.innerWidth) * 2 - 1;
  var mouseY = (event.clientY / window.innerHeight) * 2 - 1;
  //The standard offset (margins) for the pupils and keep the pupil in the eye
  var horizontalOffset = (eyeWidth - pupilWidth) - (pupilWidth/4); 
  var verticalOffset = (eyeHeight - pupilHeight) - (pupilHeight/4);
  //Calculate min and max that eye can move 
  pupilLeft = clamp(eyeWidth * mouseX, -horizontalOffset, horizontalOffset);
  pupilLeft = Math.floor(pupilLeft);
  pupilTop = clamp(eyeHeight * mouseY, -verticalOffset, verticalOffset);
  pupilTop = Math.floor(pupilTop);
  //Get all the pupils and change the margins
  pupils.forEach(pupil => { = pupilLeft+"px"; = pupilTop+"px";
    //Make sure width and height stay the same = pupilWidth+"px"; = pupilHeight+"px";

//Clamp between a min and max
function clamp(x, a, b) {
  if (x < a) return a;
  if (x > b) return b;
  return x;