Train parallax animation deconstruction

<div class="content exploded">
   <div class="layer background background-animation">
     <img src="img/bg.png" class="bordered" />
   </div>
   <div class="layer train train-animation">
     <img src="img/train.png" class="bordered" />
   </div>
   <div class="layer foreground foreground-animation">
     <img src="img/foreground.png" class="bordered" />
   </div>
   <div class="frame"></div>
 </div>

* {
  box-sizing: border-box;
}

body {
  background-color: rgb(197, 217, 255);
  overflow-x: auto;

  height: 100dvh;
  margin: 0;

  display: grid;
  place-items: center;
}

.content {
  position: relative;

  height: 600px;
  width: 200px;
}

.layer {
  position: static;
}

.background {
  transform: translateX(0);
}

.train {
  transform: translateX(-440px);
}

.foreground {
  transform: translateX(-210px);
}

.background-animation {
  animation: background-shift 4s linear 1 forwards;
}

.train-animation {
  animation: train-shift 4s linear 1 forwards;
}

.foreground-animation {
  animation: foreground-shift 4s linear 1 forwards;
}

@keyframes background-shift {
  to {
    transform: translateX(-80px);
  }
}

@keyframes train-shift {
  to {
    transform: translateX(-140px);
  }
}

@keyframes foreground-shift {
  to {
    transform: translateX(-400px);
  }
}

/* Just for demostration, not required for animation */

.frame {
  position: absolute;
  top: 0;

  width: 200px;
  aspect-ratio: 1;

  border: 3px solid rgb(0, 255, 21);
}

.exploded .frame {
  top: 2px;
}

.bordered {
  border: 2px dotted red;
}

.dg.ac {
  top: 2px !important;
  right: unset !important;
  left: 2px !important;
}

@media screen and (max-width: 600px) {
  .content {
    margin-block-start: 100px;
  }
}

const gui = new dat.GUI({ name: "My GUI" });
const content = document.getElementsByClassName("content")[0];
const layers = document.getElementsByClassName("layer");
const images = document.getElementsByTagName("img");

const config = {
  overflow: true,
  exploded: true,
  replay,
  reset,
};

gui
  .add(config, "overflow")
  .name("Overflow?")
  .onChange((newValue) => {
    if (newValue === false) {
      content.style.overflow = "hidden";
    } else {
      content.style.overflow = "visible";
    }
  });

gui
  .add(config, "exploded")
  .name("Explode?")
  .onChange((newValue) => {
    if (newValue === true) {
      const overFlowCheckbox = document.querySelector(
        "div.dg.main li:first-child input"
      );
      overFlowCheckbox.checked = true;
      overFlowCheckbox.disabled = true;

      content.style.overflow = "visible";

      for (let element of layers) {
        element.style.position = "static";
      }
    } else {
      config.overflow = false;

      const overFlowCheckbox = document.querySelector(
        "div.dg.main li:first-child input"
      );

      if (overFlowCheckbox.checked === true) {
        overFlowCheckbox.click();
      }

      overFlowCheckbox.disabled = false;

      for (let element of layers) {
        element.style.position = "absolute";
      }
    }

    document.querySelector(".content").classList.toggle("exploded");

    toggleBorders();
  });

gui
  .add(config, "replay")
  .name("Play Animation")
  .onChange(() => {
    replay();
  });

function replay() {
  reset();

  setTimeout(() => {
    layers[0].classList.add("background-animation");
    layers[1].classList.add("train-animation");
    layers[2].classList.add("foreground-animation");
  }, 20);
}

gui
  .add(config, "reset")
  .name("Reset Animation")
  .onChange(() => {
    reset();
  });

function reset() {
  layers[0].classList.remove("background-animation");
  layers[1].classList.remove("train-animation");
  layers[2].classList.remove("foreground-animation");
}

function toggleBorders() {
  for (let img of images) {
    img.classList.toggle("bordered");
  }
}

function init() {
  const overFlowCheckbox = document.querySelector(
    "div.dg.main li:first-child input"
  );
  overFlowCheckbox.disabled = true;
}

init();