How to center elements on the last row in CSS Grid?

Question

I am using CSS grid to layout some items like this...

#container {
  display: grid;
  grid-template-columns: 16.666% 16.666% 16.666% 16.666% 16.666% 16.666%;
}

.item {
  background: teal;
  color: white;
  padding: 20px;
  margin: 10px;
}

<div id="container">
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
</div>

How can I get the last row to be centered instead of left aligned? I can't guarantee the number of items so want to make the layout look right for any number of items.

Is this something I should be using flexbox for instead? Or are CSS grids a suitable use?

Answer 1

CSS Grid isn't suited for alignment across an entire row because of crisscrossing tracks blocking the way. Here's a detailed explanation:

• Aligning grid items across the entire row/column (like flex items can)

As an alternative, use flexbox with justify-content: center.

This packs all items in the horizontal center of the row. Then your margins push them apart.

On fully-filled rows, justify-content will have no effect since there's no free space for it to work.

On rows with free space (in your case, only the last row), the items are centered.

#container {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
}

.item {
  flex: 0 0 calc(16.66% - 20px);
  background: teal;
  color: white;
  padding: 20px;
  margin: 10px;
}

* {
  box-sizing: border-box;
}

<div id="container">
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
  <div class="item">Item</div>
</div>

Answer 2

Found a great article on how to Control Leftover Grid Items with Pseudo-selectors

.grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  grid-gap: 20px;
  margin: 20px;
  padding: 20px;  
}
.item {
  grid-column: span 2;
  background: #AB47BC;
  padding: 20px;
}

/* Dealing with 2 orphan items */

.item:last-child:nth-child(3n - 1) {
  grid-column-end: -2;
}

.item:nth-last-child(2):nth-child(3n + 1) {
  grid-column-end: 4;
}

/* Dealing with single orphan */

.item:last-child:nth-child(3n - 2) {
  grid-column-end: 5;
}

<div class="wrapper">
    <div class="grid grid--1">
        <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>

    <div class="grid grid--2">
        <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>
</div>