translateX()

transform: translateX(0);

transform: translateX(42px);

transform: translateX(-2.1rem);

transform: translateX(3ch);

<section id="default-example">
  <img
    class="transition-all"
    id="static-element"
    src="/shared-assets/images/examples/firefox-logo.svg"
    width="200" />
  <img
    class="transition-all"
    id="example-element"
    src="/shared-assets/images/examples/firefox-logo.svg"
    width="200" />
</section>

#static-element {
  opacity: 0.4;
  position: absolute;
}
#example-element {
  position: absolute;
}

/* <length-percentage> 値 */
transform: translateX(200px);
transform: translateX(50%);

translateX(<length-percentage>)

<div>Static</div>
<div class="moved">Moved</div>
<div>Static</div>

div {
  width: 60px;
  height: 60px;
  background-color: skyblue;
}
.moved {
  transform: translateX(10px); /* translate(10px) と等価 */
  background-color: pink;
}