Scrolling a flexbox with overflowing content

Question

Here's the code I'm using to achieve the above layout:

.header {
  height: 50px;
}

.body {
  position: absolute;
  top: 50px;
  right: 0;
  bottom: 0;
  left: 0;
  display: flex;
}

.sidebar {
  width: 140px;
}

.main {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.content {
  flex: 1;
  display: flex;
}

.column {
  padding: 20px;
  border-right: 1px solid #999;
}

<div class="header">Main header</div>
<div class="body">
  <div class="sidebar">Sidebar</div>

  <div class="main">
    <div class="page-header">Page Header. Content columns are below.</div>
    <div class="content">
      <div class="column">Column 1</div>
      <div class="column">Column 1</div>
      <div class="column">Column 1</div>
    </div>
  </div>
</div>

I omitted the code used for styling. You can see all of it in the pen.

---

The above works, but when the content area's content overflows, it makes the whole page scroll. I only want the content area itself to scroll, so I added overflow: auto to the content div.

The problem with this now is that the columns themselves don't extend beyond their parents height, so the borders are cut off there too.

Here's the pen showing the scrolling issue.

How can I set the content area to scroll independently, while still having its children extend beyond the content box's height?

Answer 1

I've spoken to Tab Atkins (author of the flexbox spec) about this, and this is what we came up with:

.content {
    flex: 1;
    display: flex;
    overflow: auto;
}

.box {
    display: flex;
    min-height: min-content; /* needs vendor prefixes */
}

<div class="content">
  <div class="box">
    <div class="column">Column 1</div>
    <div class="column">Column 2</div>
    <div class="column">Column 3</div>
  </div>
</div>

Here are the pens:

1. Short columns being stretched.
2. Longer columns overflowing and scrolling.

The reason this works is because align-items: stretch doesn't shrink its items if they have an intrinsic height, which is accomplished here by min-content.

Answer 2

I just solved this problem very elegantly after a lot of trial and error.

Check out my blog post: http://geon.github.io/programming/2016/02/24/flexbox-full-page-web-app-layout

Basically, to make a flexbox cell scrollable, you have to make all its parents overflow: hidden;, or it will just ignore your overflow settings and make the parent larger instead.

Answer 3

Working with position:absolute; along with flex:

Position the flex item with position: relative. Then inside of it, add another <div> element with:

position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;

This extends the element to the boundaries of its relative-positioned parent, but does not allow to extend it. Inside, overflow: auto; will then work as expected.

.all-0 {
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
}

p {
  text-align: justify;
}

.bottom-0 {
  bottom: 0;
}

.overflow-auto {
  overflow: auto;
}

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" rel="stylesheet" />


<div class="p-5 w-100">
  <div class="row bg-dark m-0">
    <div class="col-sm-9 p-0 d-flex flex-wrap">
      <!-- LEFT-SIDE - ROW-1 -->
      <div class="row m-0 p-0">
        <!-- CARD 1 -->
        <div class="col-md-8 p-0 d-flex">
          <div class="my-card-content bg-white p-2 m-2 d-flex flex-column">
            <img class="img img-fluid" src="https://via.placeholder.com/700x250">
            <h4>Heading 1</h4>
            <p>
              Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old...
          </div>
        </div>
        <!-- CARD 2 -->
        <div class="col-md-4 p-0 d-flex">
          <div class="my-card-content bg-white p-2 m-2 d-flex flex-column">
            <img class="img img-fluid" src="https://via.placeholder.com/400x250">
            <h4>Heading 1</h4>
            <p>
              Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old...
          </div>
        </div>
      </div>
      <div class="row m-0">
        <!-- CARD 3 -->
        <div class="col-md-4 p-0 d-flex">
          <div class="my-card-content bg-white p-2 m-2 d-flex flex-column">
            <img class="img img-fluid" src="https://via.placeholder.com/400x250">
            <h4>Heading 1</h4>
            <p>
              Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old...
          </div>
        </div>
        <!-- CARD 4 -->
        <div class="col-md-4 p-0 d-flex">
          <div class="my-card-content bg-white p-2 m-2 d-flex flex-column">
            <img class="img img-fluid" src="https://via.placeholder.com/400x250">
            <h4>Heading 1</h4>
            <p>
              Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old...
          </div>
        </div>
        <!-- CARD 5-->
        <div class="col-md-4 p-0 d-flex">
          <div class="my-card-content bg-white p-2 m-2 d-flex flex-column">
            <img class="img img-fluid" src="https://via.placeholder.com/400x250">
            <h4>Heading 1</h4>
            <p>
              Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old...
          </div>
        </div>
      </div>
    </div>
    <div class="col-sm-3 p-0">
      <div class="bg-white m-2 p-2 position-absolute all-0 d-flex flex-column">
        <h4>Social Sidebar...</h4>
        <hr />
        <div class="d-flex overflow-auto">
          <p>
            Topping candy tiramisu soufflé fruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halva fruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart.
            opping candy tiramisu soufflé fruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halva fruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut
            sweet tart. opping candy tiramisu soufflé fruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halva fruitcake ice cream chocolate bar. Bear claw ice cream chocolate
            bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halvafruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halvafruitcake ice cream chocolate bar.
            Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halvafruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halvafruitcake
            ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Topping candy tiramisu soufflé fruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart.
            Pudding cupcake danish apple pie apple pie. Halva fruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. opping candy tiramisu soufflé fruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut
            sweet tart. Pudding cupcake danish apple pie apple pie. Halva fruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. opping candy tiramisu soufflé fruitcake ice cream chocolate bar. Bear claw ice cream chocolate
            bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halva fruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halvafruitcake ice cream chocolate bar.
            Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halvafruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halvafruitcake
            ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple pie apple pie. Halvafruitcake ice cream chocolate bar. Bear claw ice cream chocolate bar donut sweet tart. Pudding cupcake danish apple
            pie apple pie. Halva
        </div>
      </div>
    </div>
  </div>

End result:

CodePen Link

Answer 4

I didn't see this answer anywhere. But the trick I needed was to make sure the items had a flex-shrink: 0; else they'll get squeezed.

.container {
  display: flex;
  overflow: auto
}

.container > * {
  flex-shrink: 0;
  width: 10em;
  height: 10em;
  background: linear-gradient(to bottom right, #F0F, #0FF);
}

<div class="container">
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
</div>

Answer 5

The following CSS changes in bold (plus a bunch of content in the columns to test scrolling) will work. Well, it makes each content column individually scrollable, which may be more (better?) than originally requested. Anyway, see the result in this Pen.

.content { flex: 1; display: flex; height: 1px; }

.column { padding: 20px; border-right: 1px solid #999; overflow: auto; }

The trick here seems to be that a scrollable panel needs to have a height literally set somewhere (in this case, via its parent), not just determined by flexbox. So even height: 1px works. The flex-grow:1 will still size the panel to fit properly.

Answer 6

A little late but this could help: http://webdesign.tutsplus.com/tutorials/how-to-make-responsive-scrollable-panels-with-flexbox--cms-23269

Basically you need to put html,body to height: 100%; and wrap all your content into a <div class="wrap"> <!-- content --> </div>

CSS:

html, body {
  height: 100%;
}
 
.wrap {
  height: 100vh;
  display: flex;
}

Answer 7

Add this:

align-items: flex-start;

to the rule for .content {}. That fixes it in your pen for me, at least (in both Firefox & Chrome).

By default, .content has align-items: stretch, which makes it size all of its auto-height children to match its own height, per http://dev.w3.org/csswg/css-flexbox/#algo-stretch. In contrast, the value flex-start lets the children compute their own heights, and align themselves at its starting edge (and overflow, and trigger a scrollbar).

Answer 8

The solution for this problem is just to add overflow: auto; to the .content for making the content wrapper scrollable.

Furthermore, there are circumstances occurring along with Flexbox wrapper and overflowed scrollable content like this codepen.

The solution is to add overflow: hidden (or auto); to the parent of the wrapper (set with overflow: auto;) around large contents.

Answer 9

One issue that I've come across is that to have a scrollbar a n element needs a height to be specified (and not as a %).

The trick is to nest another set of divs within each column, and set the column parent's display to flex with flex-direction: column.

<style>
    html, body {
        height: 100%;
        margin: 0;
        padding: 0;
    }

    body {
        overflow-y: hidden;
        overflow-x: hidden;
        color: white;
    }

    .base-container {
        display: flex;
        flex: 1;
        flex-direction: column;
        width: 100%;
        height: 100%;
        overflow-y: hidden;
        align-items: stretch;
    }

    .title {
        flex: 0 0 50px;
        color: black;
    }

    .container {
        flex: 1 1 auto;
        display: flex;
        flex-direction: column;
    }

        .container .header {
            flex: 0 0 50px;
            background-color: red;
        }

        .container .body {
            flex: 1 1 auto;
            display: flex;
            flex-direction: row;
        }

            .container .body .left {
                display: flex;
                flex-direction: column;
                flex: 0 0 80px;
                background-color: blue;
            }
                .container .body .left .content,
                .container .body .main .content,
                .container .body .right .content {
                    flex: 1 1 auto;
                    overflow-y: auto;
                    height: 100px;
                }
                .container .body .main .content.noscrollbar {
                    overflow-y: hidden;
                }

            .container .body .main {
                display: flex;
                flex-direction: column;
                flex: 1 1 auto;
                background-color: green;
            }

            .container .body .right {
                display: flex;
                flex-direction: column;
                flex: 0 0 300px;
                background-color: yellow;
                color: black;
            }

    .test {
        margin: 5px 5px;
        border: 1px solid white;
        height: calc(100% - 10px);
    }
</style>

And here's the html:

<div class="base-container">
    <div class="title">
        Title
    </div>
    <div class="container">
        <div class="header">
            Header
        </div>
        <div class="body">
            <div class="left">
                <div class="content">
                    <ul>
                        <li>1</li>
                        <li>2</li>
                        <li>3</li>
                        <li>4</li>
                        <li>5</li>
                        <li>6</li>
                        <li>7</li>
                        <li>8</li>
                        <li>9</li>
                        <li>10</li>
                        <li>12</li>
                        <li>13</li>
                        <li>14</li>
                        <li>15</li>
                        <li>16</li>
                        <li>17</li>
                        <li>18</li>
                        <li>19</li>
                        <li>20</li>
                        <li>21</li>
                        <li>22</li>
                        <li>23</li>
                        <li>24</li>
                    </ul>
                </div>
            </div>
            <div class="main">
                <div class="content noscrollbar">
                    <div class="test">Test</div>
                </div>
            </div>
            <div class="right">
                <div class="content">
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>Right</div>
                    <div>End</div>
                </div>
            </div>
        </div>
    </div>
</div>

https://jsfiddle.net/LiamFlavelle/czpjdfr4/

Answer 10

I tried a lot of the answers above without much joy. I suspect that a lot of these answers are out of date or just didn't fit my requirements. The answer to my problem came from a related question:

The Automatic Minimum Size of Flex Items

You're encountering a flexbox default setting.

A flex item cannot be smaller than the size of its content along the main axis.

So the thing that was preventing my flex box item from scrolling was that the size of the element would automatically adjust to auto based on the content and then resize, not scroll. Here's a fully working modern example (using tailwind):

<!DOCTYPE html>
<html class="h-full">
    <head>
        <script src="https://cdn.tailwindcss.com"></script>
    </head>
    <body class="h-full">
        <div class="h-full flex flex-col items-stretch">
            <div class="bg-white border-b border-gray-400">
              <h1>
                Header
              </h1>
            </div>
            <div class="flex flex-row flex-auto min-h-0">
                <div class="flex flex-col bg-red-600 items-stretch min-h-0" style="flex: 0 0 25%;">
                    <div class="flex-initial min-h-0 overflow-x-hidden overflow-y-auto">
                        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque feugiat libero id elementum iaculis. Vestibulum at mauris mauris. Donec blandit nibh rhoncus mollis mattis. Aenean gravida ex sagittis semper aliquet. Suspendisse a dolor enim. Fusce sagittis lectus et eleifend imperdiet. Curabitur iaculis pellentesque rutrum. Fusce et gravida eros. Nam vestibulum pharetra lorem, sed semper leo fermentum nec.</p>
                        
                        <p>Curabitur varius feugiat maximus. Morbi dolor urna, consectetur ac nisl eget, varius pretium sem. Curabitur aliquam, lectus ut viverra consequat, dolor ligula gravida ex, nec dictum felis mi in enim. Curabitur luctus ligula diam, sed varius orci vehicula a. Ut vehicula imperdiet tempor. Morbi eget sollicitudin mi. Etiam condimentum sem arcu, non dignissim mi ultricies ut. Fusce faucibus sem nec laoreet facilisis. Nullam ut lorem vitae odio gravida rhoncus. Etiam ut orci vitae odio interdum consequat.</p>
                        
                        <p>Sed felis dui, fermentum ac libero ut, faucibus mattis urna. Morbi at est lobortis, lobortis diam nec, rhoncus augue. Sed at turpis malesuada nulla accumsan accumsan. Mauris pharetra, odio at elementum pharetra, lacus magna luctus sem, sit amet pretium lorem lectus sed libero. Curabitur ullamcorper turpis nunc, a eleifend urna venenatis ac. Vivamus consectetur, nunc quis facilisis vehicula, risus ligula finibus arcu, at vulputate ex dui lobortis dolor. Maecenas tincidunt, lacus et vehicula pulvinar, enim sem venenatis nisi, nec fringilla eros felis quis mauris. Duis luctus eu risus condimentum rutrum. Suspendisse interdum at velit eget mattis. Integer quis porta nisl. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Nunc iaculis, lacus ut dignissim imperdiet, enim enim malesuada quam, id pretium justo neque id ipsum. Vestibulum nec nisl mattis, mattis est sed, venenatis lectus. Quisque sed magna nec purus viverra rhoncus dapibus sed sapien. Quisque id fermentum risus, non vestibulum justo. Donec ultrices enim quis eros porttitor, non posuere tortor viverra.</p>
                        
                        <p>Phasellus leo ipsum, tristique nec tristique sit amet, molestie eget urna. Aenean suscipit eget ante in vulputate. Morbi tincidunt velit quis lorem gravida, ac scelerisque massa aliquet. Aliquam sem lacus, bibendum ut elit at, mollis dapibus ligula. Suspendisse potenti. Fusce neque est, lobortis a augue a, pretium fermentum turpis. Etiam molestie et odio non rhoncus. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Vivamus condimentum cursus metus eu hendrerit. Vestibulum ultrices, leo eget consectetur tempus, nisi diam maximus orci, sit amet ultricies leo mauris vitae eros.</p>
                        
                        <p>Aenean eleifend pretium libero ut venenatis. Quisque maximus nulla eget arcu maximus, id rhoncus lectus lobortis. Nullam at ullamcorper nisi. Aliquam erat volutpat. Curabitur efficitur ante in fermentum euismod. Donec id arcu finibus, finibus mauris id, tempor nisl. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Nam lobortis feugiat ligula, id aliquet elit placerat ut. In ac mi elementum, varius urna a, condimentum urna. Sed luctus massa nulla, quis elementum sapien lacinia eu. Vestibulum risus leo, rutrum ac finibus in, iaculis at ligula. Nullam hendrerit mattis eleifend. Sed egestas lectus eu vulputate malesuada.</p>
                    </div>
                </div>
                    
                <div class="flex flex-col items-stretch min-h-0 flex-auto">
                    <div class="flex-initial min-h-0 overflow-x-hidden overflow-y-auto">
                        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque feugiat libero id elementum iaculis. Vestibulum at mauris mauris. Donec blandit nibh rhoncus mollis mattis. Aenean gravida ex sagittis semper aliquet. Suspendisse a dolor enim. Fusce sagittis lectus et eleifend imperdiet. Curabitur iaculis pellentesque rutrum. Fusce et gravida eros. Nam vestibulum pharetra lorem, sed semper leo fermentum nec.</p>
                        
                        <p>Curabitur varius feugiat maximus. Morbi dolor urna, consectetur ac nisl eget, varius pretium sem. Curabitur aliquam, lectus ut viverra consequat, dolor ligula gravida ex, nec dictum felis mi in enim. Curabitur luctus ligula diam, sed varius orci vehicula a. Ut vehicula imperdiet tempor. Morbi eget sollicitudin mi. Etiam condimentum sem arcu, non dignissim mi ultricies ut. Fusce faucibus sem nec laoreet facilisis. Nullam ut lorem vitae odio gravida rhoncus. Etiam ut orci vitae odio interdum consequat.</p>
                        
                        <p>Sed felis dui, fermentum ac libero ut, faucibus mattis urna. Morbi at est lobortis, lobortis diam nec, rhoncus augue. Sed at turpis malesuada nulla accumsan accumsan. Mauris pharetra, odio at elementum pharetra, lacus magna luctus sem, sit amet pretium lorem lectus sed libero. Curabitur ullamcorper turpis nunc, a eleifend urna venenatis ac. Vivamus consectetur, nunc quis facilisis vehicula, risus ligula finibus arcu, at vulputate ex dui lobortis dolor. Maecenas tincidunt, lacus et vehicula pulvinar, enim sem venenatis nisi, nec fringilla eros felis quis mauris. Duis luctus eu risus condimentum rutrum. Suspendisse interdum at velit eget mattis. Integer quis porta nisl. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Nunc iaculis, lacus ut dignissim imperdiet, enim enim malesuada quam, id pretium justo neque id ipsum. Vestibulum nec nisl mattis, mattis est sed, venenatis lectus. Quisque sed magna nec purus viverra rhoncus dapibus sed sapien. Quisque id fermentum risus, non vestibulum justo. Donec ultrices enim quis eros porttitor, non posuere tortor viverra.</p>
                        
                        <p>Phasellus leo ipsum, tristique nec tristique sit amet, molestie eget urna. Aenean suscipit eget ante in vulputate. Morbi tincidunt velit quis lorem gravida, ac scelerisque massa aliquet. Aliquam sem lacus, bibendum ut elit at, mollis dapibus ligula. Suspendisse potenti. Fusce neque est, lobortis a augue a, pretium fermentum turpis. Etiam molestie et odio non rhoncus. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Vivamus condimentum cursus metus eu hendrerit. Vestibulum ultrices, leo eget consectetur tempus, nisi diam maximus orci, sit amet ultricies leo mauris vitae eros.</p>
                        
                        <p>Aenean eleifend pretium libero ut venenatis. Quisque maximus nulla eget arcu maximus, id rhoncus lectus lobortis. Nullam at ullamcorper nisi. Aliquam erat volutpat. Curabitur efficitur ante in fermentum euismod. Donec id arcu finibus, finibus mauris id, tempor nisl. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Nam lobortis feugiat ligula, id aliquet elit placerat ut. In ac mi elementum, varius urna a, condimentum urna. Sed luctus massa nulla, quis elementum sapien lacinia eu. Vestibulum risus leo, rutrum ac finibus in, iaculis at ligula. Nullam hendrerit mattis eleifend. Sed egestas lectus eu vulputate malesuada.</p>

                    </div>
                </div>
            </div>
          </div>
    </body>
</html>

Which renders like this in Chrome (100)

Answer 11

.list-wrap {
  width: 355px;
  height: 100%;
  position: relative;

  .list {
    position: absolute;
    top: 0;
    bottom: 0;
    overflow-y: auto;
    width: 100%;
  }
}

Answer 12

Here's my take on it, leaving it here for others. I am using Bootstrap 4 in this example (for the classes reference). I needed to add in a flex:1 in my case for it to properly scroll and some specific height to the parent container (not a %). I'm still not sure why flex:1 is needed since its essentially just flex-grow:1 and setting flex-basis:0%.

<div
  class="flex-parent-container d-flex flex-column flex-column-fluid"
  style="height: 80vh" ----> set some arbitrary value on the parent container
>
  <h1
    class="my-10 border-bottom-dashed border-gray-300 p-5 py-10"
    style="font-size: 24px"
  >
    Lorem Ipsum
  </h1>
  <div
    class="flex-parent d-flex flex-column flex-column-fluid gap-10 p-5 scroll-y"
    style="font-size: 14px; flex: 1; overflow-y: auto" ----> flex: 1 is required!
  >
    <div
      class="flex-item d-flex flex-row fluid justify-content-between selected p-7"
    ></div>
  </div>
</div>

Answer 13

As people have noted the accepted answer CodePens no longer work. I looked into why this might be and have them working below:

1. Short columns being stretched
2. Long columns scrolling

The changes were simple:

For 1. Short columns being stretched, although the current gist works it no longer needs the min-height property on .box.

.box {
  display: flex;
}

The inspector indicates that --webkit-min-content is an invalid property value and is ignored. min-content is already supported by newer browsers. This works without having to specify height anymore. The flex property of the content div makes it grow to the bottom of the viewport.

For 2. Long columns scrolling, change min-height: -webkit-min-content; to height: min-content

.box {
  height: fit-content;
  min-height: 100%;
  display: flex;
}

It appears that only setting min-height: fit-content; doesn't work. This could be a bug with min-height. I tested this with both Chrome and Firefox. The behavior is the same in both browsers with min-height failing.

Setting the min-height to 100% makes the column borders extend even if the column is shorter than the .box div.