Can Auto Margins Work in CSS Grid Like They Do in Flexbox

Can auto margins work in CSS Grid like they do in Flexbox?

There is a way to get your request, that can be considered a little bit hackish, but that is effective.

Create an arbitrary number of unused rows between all the list elements and the last one. Here a snippet that will work as far as the list has less than 99 elements:

ul {

  list-style-type: none;

  padding: 0;

  display: grid;

  outline: 1px solid red;

  height: 150px;

  background-color: lime;

  grid-template-rows: repeat(99, max-content) 1fr [last];

}

li {

  background-color: cornsilk;

}

li:last-of-type {

  grid-row: last;

}

<ul>

  <li>1</li>

  <li>2</li>

  <li>3</li>

  <li>4</li>

</ul>

<ul>

  <li>1</li>

  <li>2</li>

  <li>3</li>

</ul>

Why do block elements with margin auto behave differently inside a grid?

From the specification:

By default, grid items stretch to fill their grid area. However, if justify-self or align-self compute to a value other than stretch or margins are auto, grid items will auto-size to fit their contents.

Better way to set distance between flexbox items

Flexbox doesn't have collapsing margins.
Flexbox doesn't have anything akin to border-spacing for tables (edit: CSS property gap fulfills this role in newer browsers, Can I use)

Therefore achieving what you are asking for is a bit more difficult.

In my experience, the "cleanest" way that doesn't use :first-child/:last-child and works without any modification on flex-wrap:wrap is to set padding:5px on the container and margin:5px on the children. That will produce a 10px gap between each child and between each child and their parent.

Demo

.upper {
  margin: 30px;
  display: flex;
  flex-direction: row;
  width: 300px;
  height: 80px;
  border: 1px red solid;

  padding: 5px; /* this */
}

.upper > div {
  flex: 1 1 auto;
  border: 1px red solid;
  text-align: center;

  margin: 5px;  /* and that, will result in a 10px gap */
}

.upper.mc /* multicol test */ {
  flex-direction: column;
  flex-wrap: wrap;
  width: 200px;
  height: 200px;
}

<div class="upper">
  <div>aaa<br/>aaa</div>
  <div>aaa</div>
  <div>aaa<br/>aaa</div>
  <div>aaa<br/>aaa<br/>aaa</div>
  <div>aaa</div>
  <div>aaa</div>
</div>

<div class="upper mc">
  <div>aaa<br/>aaa</div>
  <div>aaa</div>
  <div>aaa<br/>aaa</div>
  <div>aaa<br/>aaa<br/>aaa</div>
  <div>aaa</div>
  <div>aaa</div>
</div>

Areas covered by Flexbox which are difficult or impossible to achieve with Grid

Advantage Flexbox

Here are 13 areas where flexbox comes out ahead of Grid (Level 1):

Centering wrapped items. Imagine five elements. Only four per row. The fifth one wraps. In a flex container, that fifth one can be easily aligned across the entire row with justify-content. Try centering this fifth item in a grid container. Not a simple matter.
- Aligning grid items across the entire row/column (like flex items can)
- How to center elements on the last row in CSS Grid?
- How to offset a grid item, also shifting its siblings?
- Can I have a varying number of columns per row in a CSS grid?

Wrapping. Flex items of variable lengths have no problem wrapping. Try getting grid items of variable lengths to wrap. Not possible.
- How to get grid items of different lengths to wrap?
- Can grid items wrap?

Auto margins. Flex items can be placed, packed and spaced away throughout their container with auto margins. Grid items, however, are confined to their tracks, greatly diminishing the utility of auto margins.
- Can auto margins work in CSS Grid like they do in Flexbox?

Min, Max, Default – all in one. Setting the min-width, max-width and default width of a flex item is easy. How can all three lengths be set on a grid column or row? They can't.
- Setting the minimum, maximum and default length of a grid column / row
- Set minimum and maximum widths to grid column using percentages (related, but not exactly the same problem)

Sticky footer / header. It's just so much simpler and easier to pin a footer or header with flexbox.
- How can I have a sticky footer with my CSS Grid layout?

Consuming remaining space. A flex item can consume remaining space with flex-grow. Grid items have no such function.
- Aligning grid items across the entire row/column (like flex items can)
- Make grid item use remaining space like flex item with flex-grow: 1
- How to make the items in the last row consume remaining space in CSS Grid?
- How to make CSS Grid last row to take up remaining space
- Hiding a left column in CSS Grid
- How to get the effect of grid layout's grid-template-columns with a variable number of columns?
- CSS fr / fractional units minimum too large

Shrinking. Flex has flex-shrink. Grid has... nothing.
- Shrink grid items just like flex items in css

Limiting the column count in a dynamic layout. With flexbox, creating a wrapping two-column grid that remains fixed at two-columns across screen sizes is no problem. In Grid, despite having all these great functions, such repeat(), auto-fill and minmax(), it can't be done.
- Make CSS Grid auto-fill only 2 columns
- CSS grid - maximum number of columns without media queries

Creating space between first and last items. In a grid container with a variable number of columns, it's not easy to add an empty first and last column. Margins, padding, columns and pseudo elements each have their limitations. It's simple and easy with flexbox.
- Add space before and after first and last grid items

An important benefit of the inline-level container is lost in some cases. If you have a Grid layout with a dynamic number of columns – meaning you cannot set the number of columns or a width for the container – then display: inline-grid doesn't work. All items stack in a single column. This is because the default setting on grid-auto-columns is one column. In at least some cases, flexbox fixes the problem.
- How to make a grid container shrink to fit the content?

Getting columns with author-defined grid areas to wrap without media queries. Let's say you have a two-column grid containing grid areas that have set locations, and want the grid to automatically transition to a single column (with the second column wrapping below the first) on smaller screens. With grid, you would need a media query. The auto-fill and auto-fit functions will not work because the locations of grid areas have been specified. If you want to avoid a media query, flexbox's flex-wrap function may be useful.
- Two-Column grid should wrap into One-Column grid

There is no column-reverse function in CSS Grid. Getting items to populate a container starting from the bottom isn't possible with a single rule applied to the grid container. With flexbox, however, the task is simple with flex-direction: column-reverse.
- Filling cells starting from the bottom in CSS Grid
- https://stackoverflow.com/q/67620185/3597276

The resize property on a grid item has no effect on the track. Unless a column or row track is set to auto (content-based sizing), resizing a grid item will overflow the track. Since flexbox doesn't have column and row tracks, it may be a useful alternative.
- Resize property on grid items results in overlap of other grid items

Using margin on flex items

You need to do it with padding - which, when in border-box mode does not make the container larger than it's specified width - not margin, and a nested flex div. This is how all flexbox-based grid systems work. Code below:

.flex-container{

    border: 1px solid red;

    box-sizing: border-box;

    display: flex;

    flex-wrap: wrap;

    width: 320px;

}

.flex-item{

    padding:1em;

    box-sizing: border-box;

    height: 160px;

    width: 50%;

    display:flex;

}

.flex-item>div {

    border: 1px solid blue;

    flex: 1 1 auto;

}

<div class="flex-container">

    <div class="flex-item"><div></div></div>

    <div class="flex-item"><div></div></div>

    <div class="flex-item"><div></div></div>

    <div class="flex-item"><div></div></div>

    <div class="flex-item"><div></div></div>

    <div class="flex-item"><div></div></div>

</div>

Can Auto Margins Work in CSS Grid Like They Do in Flexbox