问如何在我的内容下创建广告横幅CSS？

EN

const check = () => {
  let firstBoxInput = document.querySelector('.first-child-width').value;
  let secondBoxInput = document.querySelector('.second-child-width').value;

  const firstBox = document.querySelector('.first-child');
  const secondBox = document.querySelector('.second-child');

  firstBox.style.width = `${firstBoxInput}px`;
  secondBox.style.width = `${secondBoxInput}px`;
};

document.querySelector('button').addEventListener('click', check);

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

.container {
  display: flex;
  flex-wrap: wrap;
  width: 520px;
  border: 1px solid black
}

.container .first-child {
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: orange;
  border: 1px solid black;
  width: 300px;
  height: 300px
}

.container .second-child {
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: green;
  border: 1px solid black;
  width: 200px;
  height: 300px
}

<input type="number" class="first-child-width" placeholder="First Box Width in px">
<input type="number" class="second-child-width" placeholder="Second Box Width in px">
<button type="button">Click</button>

<section class="container">
  <article class="first-child">First Child</article>
  <article class="second-child">Second Child</article>
</section>

.container{
  display: flex;
  flex-direction: row;
}

.text{
  text-align: justify;
   padding: 0 10px;
}

.adsense{
  width:100px;
  background-color:#666;
  color:#ffffff;
}
@media (max-width: 600px) {
.container{
  flex-direction: column;
}
.adsense{
  margin-top:20px;
  width:100%;
  height:200px;
  background-color:#666;
  color:#ffffff;
  }
}

<div class="container">
<div class='text'>
<h3>My Content</h3>
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
</div>
<div class='adsense'>
adsense
</div>

</div>