Elements centered within a flex container are expanding and overflowing above

Question

Elements centered within a flex container are expanding and overflowing above

It seems like I'm missing a key point when it comes to my flexbox setup for vertical and horizontal centering.

The issue arises when the container's height exceeds that of its parent, causing the content to extend beyond the top but remain fixed at the bottom due to the presence of a vertical scroll. Give it a try by adjusting the view's height or adding more lines of text.

body,
html {
  height: 100%;
  width: 100%;
  margin: 0;
}

* {
  box-sizing: border-box;
}

#wrapper {
  background: grey;
  height: 100%;
  width: 100%;
  max-height: 100%;
  display: flex;
  overflow-y: auto;
  align-items: center;
  justify-content: center;
}

#box {
  margin: 30px 0;
  background: white;
  border: 1px solid #dfdfdf;
}

<div id="wrapper">
  <div id="box">
    First line
    <br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br> Last linje
  </div>
</div>

I need help preventing the clipping issue. Additionally, I aim to maintain a 30px margin above and below the container. Any suggestions would be greatly appreciated!

Thank you!

html css flexbox

Answer 1

Answer №1

It's not that you forgot something, but rather a matter of understanding what is going on. Initially, you set your wrapper to be 100% height of the screen and then centered the box both vertically and horizontally. However, when the box has a large height, it can result in a layout like this:

https://i.sstatic.net/ZlCbT.png

By adding overflow-y: auto, you are creating a scroll within the wrapper that starts from the top and allows you to scroll through the overflowing content at the bottom, leading to a visualization like this:

https://i.sstatic.net/tkgBQ.png

This explains why you can scroll to see the bottom part but struggle to view the top part. To resolve this issue, it's recommended to utilize margin:auto for centering your element, which results in two scenarios:

If box-height < wrapper-height, the space will be evenly distributed on each side due to margin:auto, thereby centering your element as expected.
For box-height > wrapper-height, the normal behavior occurs where the element overflows and its top edge aligns with the top edge of the wrapper.

https://i.sstatic.net/UHMB8.png

You might also observe similar issues with horizontal alignment, which is why utilizing margin for centering in both directions can be beneficial.

body,
html {
  height: 100%;
  width: 100%;
  margin: 0;
}

* {
  box-sizing: border-box;
}

#wrapper {
  background: grey;
  height: 100%;
  width: 100%;
  max-height: 100%;
  padding:30px 0;
  display: flex;
  overflow-y: auto;
}

#box {
  margin: auto;
  background: white;
  border: 1px solid #dfdfdf;
}

<div id="wrapper">
  <div id="box">
    First line
    <br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br> Last linje
  </div>
</div>

Answer 2

It's not that you forgot something, but rather a matter of understanding what is going on. Initially, you set your wrapper to be 100% height of the screen and then centered the box both vertically and horizontally. However, when the box has a large height, it can result in a layout like this:

https://i.sstatic.net/ZlCbT.png

By adding overflow-y: auto, you are creating a scroll within the wrapper that starts from the top and allows you to scroll through the overflowing content at the bottom, leading to a visualization like this:

https://i.sstatic.net/tkgBQ.png

This explains why you can scroll to see the bottom part but struggle to view the top part. To resolve this issue, it's recommended to utilize margin:auto for centering your element, which results in two scenarios:

If box-height < wrapper-height, the space will be evenly distributed on each side due to margin:auto, thereby centering your element as expected.
For box-height > wrapper-height, the normal behavior occurs where the element overflows and its top edge aligns with the top edge of the wrapper.

https://i.sstatic.net/UHMB8.png

You might also observe similar issues with horizontal alignment, which is why utilizing margin for centering in both directions can be beneficial.

body,
html {
  height: 100%;
  width: 100%;
  margin: 0;
}

* {
  box-sizing: border-box;
}

#wrapper {
  background: grey;
  height: 100%;
  width: 100%;
  max-height: 100%;
  padding:30px 0;
  display: flex;
  overflow-y: auto;
}

#box {
  margin: auto;
  background: white;
  border: 1px solid #dfdfdf;
}

<div id="wrapper">
  <div id="box">
    First line
    <br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br> Last linje
  </div>
</div>

Answer 3

Answer №2

To achieve the desired effect of giving your flex item (#box) a specific height and setting its overflow, rather than modifying the flex container, you can make some adjustments to your styles. Additionally, to incorporate the 30px spacing above and below, it's recommended to remove the margin from the box and instead apply padding to the container.

Here is how the updated styles would appear:

#wrapper {
  background: grey;
  height: 100%;
  width: 100%;
  max-height: 100%;
  display: flex;      
  align-items: center;
  justify-content: center;
  padding: 30px 0; /*added*/
}

#box {
  background: white;
  border: 1px solid #dfdfdf;
  overflow-y: auto; /*added*/
  height: 100%; /*added*/
}

body,
html {
  height: 100%;
  width: 100%;
  margin: 0;
}

* {
  box-sizing: border-box;
}

#wrapper {
  background: grey;
  height: 100%;
  width: 100%;
  max-height: 100%;
  display: flex;      
  align-items: center;
  justify-content: center;
  padding: 30px 0;
}

#box {    
  background: white;
  border: 1px solid #dfdfdf;
  overflow-y: auto;
  height: 100%;
}

<div id="wrapper">
  <div id="box">
    First line
    <br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br> Last linje
  </div>
</div>

Answer 4

To achieve the desired effect of giving your flex item (#box) a specific height and setting its overflow, rather than modifying the flex container, you can make some adjustments to your styles. Additionally, to incorporate the 30px spacing above and below, it's recommended to remove the margin from the box and instead apply padding to the container.

Here is how the updated styles would appear:

#wrapper {
  background: grey;
  height: 100%;
  width: 100%;
  max-height: 100%;
  display: flex;      
  align-items: center;
  justify-content: center;
  padding: 30px 0; /*added*/
}

#box {
  background: white;
  border: 1px solid #dfdfdf;
  overflow-y: auto; /*added*/
  height: 100%; /*added*/
}

body,
html {
  height: 100%;
  width: 100%;
  margin: 0;
}

* {
  box-sizing: border-box;
}

#wrapper {
  background: grey;
  height: 100%;
  width: 100%;
  max-height: 100%;
  display: flex;      
  align-items: center;
  justify-content: center;
  padding: 30px 0;
}

#box {    
  background: white;
  border: 1px solid #dfdfdf;
  overflow-y: auto;
  height: 100%;
}

<div id="wrapper">
  <div id="box">
    First line
    <br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br>line<br> Last linje
  </div>
</div>

Answer 5

Answer №3

It appears that the top margin within the box class is causing the container's height to increase. Consider adjusting it to padding instead of margin for a better result. I hope this suggestion proves helpful. Many thanks.

Answer 6

It appears that the top margin within the box class is causing the container's height to increase. Consider adjusting it to padding instead of margin for a better result. I hope this suggestion proves helpful. Many thanks.

Elements centered within a flex container are expanding and overflowing above

Answer №1

Answer №2

Answer №3

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