Display list of elements as table with CSS only?

Question

Display list as a table with 3 columns, with the items evenly spread, and having 10px margin from every sides and between rows.

.item { width: 10px; height: 10px; background: black; }
.grid { background: #eee; }

<div class="grid">
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
</div>

Should be rendered as

It is possible to achieve that with flex layout, but it would require more complicated HTML, see example below.

.item { width: 10px; height: 10px; background: black; }

.grid { background: #eee; padding: 10px 10px 0 10px; }
.row { display: flex; justify-content: space-between; padding: 0 0 10px 0;  }

<div class="grid">
  <div class="row">
    <div class="item"></div>
    <div class="item"></div>
    <div class="item"></div>
  </div>
  <div class="row">
    <div class="item"></div>
    <div class="item"></div>
    <div class="item"></div>
  </div>
 </div>

I wonder if it would be possible to do with pure CSS, without adding any additional HTML elements. The size of .items shouldn't be changed, and it's unknown.

Answer 1

You can do this with flexbox by adding a hidden element between the first and last row that will be width:100% thus you will avoid changing the html:

.item {
  width: 10px;
  height: 10px;
  background: black;
}

.row {
  display: flex;
  justify-content: space-between;
  padding: 10px;
  background: #eee;
  flex-wrap: wrap;
}

.row:after {
  content: "";
  width: 100%;
  height: 10px;
}

.row :nth-child(n + 4) {
  order: 1;
}

<div class="row">
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
</div>

If the number of element is unknown you can consider CSS grid:

.item {
  width: 10px;
  height: 10px;
  background: black;
}
.row {
  display: grid;
  grid-template-columns: repeat(3,1fr);
  grid-gap: 10px;
  padding:10px;
  background: #eee;
}
.row :nth-child(3n + 2) {
  margin:auto;
}
.row :nth-child(3n + 3) {
  margin-left:auto;
}

<div class="row">
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
</div>

Answer 2

Temani Afif has written a good answer. The flexbox one will work only for 2 to 3 rows but the grid version will work for more items.

The grid CSS can be simplified further by using space-between, thus getting rid of margins and n-th child selectors.

.item {
   width: 10px;
   height: 10px;
   background: black;
}
   
.row {
   display: grid;
   grid-template-columns: repeat(3,10px); /*change this*/
   grid-gap: 10px;
   padding:10px;
   background: #eee;
   justify-content: space-between;  /*add this*/
 }
  

<div class="row">
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
</div>