How to make CSS Sticky work with Flex issue - html

Question

I have an HTML structure where I can't seem to get the CSS position sticky working.
I think it because it's within the aside container. If I make aside stick it works.
I want the .product-info div to be sticky and when it hits the div .content-other it unsticks.
Unless with flex I could move out .personal-info and .product-info from within the aside and have them sit to the right on top of each other? Like
content | Personal info
| Product info
Then not bother having the wrapping aside? Not sure how to stack these like this though with flex.
body {
padding: 20px;
}
.container {
margin-left: auto;
margin-right: auto;
position: relative;
padding-bottom: 16px;
padding-top: 16px;
width: 100%;
display: flex;
}
.content {
position: relative;
max-width: 100%;
flex-basis: 74%;
border: 1px solid black;
width: 300px;
margin-right: 20px;
height: 540px;
}
.right-side {
align-self: flex-start;
background-color: #ffffff;
border: 2px solid #e8e8e3;
border-radius: 0 4px 4px 4px;
flex: 1 1;
flex-basis: 40%;
min-width: 338px;
padding: 16px 16px 0;
display: block;
width: 400px;
}
.personal-info {
height: 250px;
}
.product-info {
position: sticky;
position: -webkit-sticky;
top: 24px;
border: 1px solid red;
}
.content-other {
width: 100%;
background: #f5f5f5;
height: 400px;
}
<div class="container">
<div class="content">content area here</div>
<aside class="right-side">
<div class="personal-info">some info</div>
<div class="product-info">sticky info</div>
</aside>
</div>
<div class="content-other">.product-info unsticks when it hits here</div>
Cheers

Answer 1

Simply remove align-self: flex-start;
body {
padding: 20px;
}
.container {
margin-left: auto;
margin-right: auto;
position: relative;
padding-bottom: 16px;
padding-top: 16px;
width: 100%;
display: flex;
}
.content {
position: relative;
max-width: 100%;
flex-basis: 74%;
border: 1px solid black;
width: 300px;
margin-right: 20px;
height: 540px;
}
.right-side {
/*align-self: flex-start;*/
background-color: #ffffff;
border: 2px solid #e8e8e3;
border-radius: 0 4px 4px 4px;
flex: 1 1;
flex-basis: 40%;
min-width: 338px;
padding: 16px 16px 0;
display: block;
width: 400px;
}
.personal-info {
height: 250px;
}
.product-info {
position: sticky;
position: -webkit-sticky;
top: 24px;
border: 1px solid red;
}
.content-other {
width: 100%;
background: #f5f5f5;
height: 400px;
}
<div class="container">
<div class="content">content area here</div>
<aside class="right-side">
<div class="personal-info">some info</div>
<div class="product-info">sticky info</div>
</aside>
</div>
<div class="content-other">.product-info unsticks when it hits here</div>