CSS Scroll Anchoring

.whole-content-wrapper {
  display: flex;
  flex-direction: column;
  height: 100%;
  width: 100%;
}

#example-element {
  height: 100%;
  border: 2px dashed dodgerblue;
  padding: 0.75em;
  text-align: left;
  overflow: scroll;
}

#playback {
  font-size: 1em;
  width: 10em;
  height: 4em;
  font-weight: bold;
  margin: 1em auto;
  background-color: aliceblue;
  border: solid 2px dodgerblue;
  border-radius: 5px;
}

#playback:hover {
  border-color: lightseagreen;
}

#playback:active {
  filter: brightness(0.9);
}

<section class="default-example" id="default-example">
  <div class="whole-content-wrapper">
    <button id="playback" type="button">Start lottery</button>
    <p>Magic numbers for today are:</p>
    <div id="example-element"></div>
  </div>
</section>

const example = document.getElementById("example-element");
const button = document.getElementById("playback");
let intervalId;

function setInitialState() {
  example.innerHTML = "";
  Array.from({ length: 10 }, (_, i) => i).forEach(addContent);
  example.scrollTop = example.scrollHeight;
}

function addContent() {
  console.log("adding content");
  const magicNumber = Math.floor(Math.random() * 10000);
  example.insertAdjacentHTML(
    "afterbegin",
    `<div class="new-content-container">New Magic Number: ${magicNumber}</div>`,
  );
}

button.addEventListener("click", () => {
  if (example.classList.contains("running")) {
    example.classList.remove("running");
    button.textContent = "Start lottery";
    clearInterval(intervalId);
  } else {
    example.classList.add("running");
    button.textContent = "Stop lottery";
    setInitialState();
    intervalId = setInterval(addContent, 1000);
  }
});