Would be great if we could see what code you have written for your implementation.
However, I have also included my own minimalistic implementation to recreate the effect you are looking for. Not pretty, but you can use it as a base template.
传真
<section class="section-a"></section>
<section class="section-b">
<div class="left">
<p>Some text content</p>
<p>Some text content</p>
<p>Some text content</p>
<p>Some text content</p>
<p>Some text content</p>
<p>Some text content</p>
</div>
<div class="right">
<p>Some text content</p>
<p>Some text content</p>
<p>Some text content</p>
<p>Some text content</p>
<p>Some text content</p>
<p>Some text content</p>
</div>
</section>
<section class="section-c"></section>
CSS
body {
margin: 0;
}
section {
width: 100vw;
border: 2px solid;
}
.section-a {
height: 100vh;
background-color: red;
}
.section-b {
height: 150vh;
display: flex;
background-color: green;
}
.section-c {
height: 100vh;
background-color: blue;
}
.left {
height: 100vh;
width: 30%;
background: purple;
position: sticky;
top: 0;
}
.right {
height: 100%;
width: 70%;
}
https://codepen.io/Jun-Wen-Soh/pen/KKEMNvJ