<div class="container">
    <div class="square"></div>
  </div>

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

.container {
  width: 100%;
  height: 100vh;
}

.square {
  width: 100px;
  height: 100px;
  background-color: blue;
}

gsap.to(".square", { duration: 1, x: 200 })