place-items - CSS: Cascading Style Sheets 编辑

The CSS place-items shorthand property allows you to align items along both the block and inline directions at once (i.e. the align-items and justify-items properties) in a relevant layout system such as Grid or Flexbox. If the second value is not set, the first value is also used for it.

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Constituent properties

This property is a shorthand for the following CSS properties:

• align-items
• justify-items

Syntax

/* Keyword values */
place-items: auto center;
place-items: normal start;

/* Positional alignment */
place-items: center normal;
place-items: start auto;
place-items: end normal;
place-items: self-start auto;
place-items: self-end normal;
place-items: flex-start auto;
place-items: flex-end normal;
place-items: left auto;
place-items: right normal;

/* Baseline alignment */
place-items: baseline normal;
place-items: first baseline auto;
place-items: last baseline normal;
place-items: stretch auto;

/* Global values */
place-items: inherit;
place-items: initial;
place-items: unset;

Values

auto

The value used is the value of the justify-items property of the parents box, unless the box has no parent, or is absolutely positioned, in these cases, auto represents normal.

normal

The effect of this keyword is dependent of the layout mode we are in:

• In block-level layouts, the keyword is a synonym of start.
• In absolutely-positioned layouts, the keyword behaved like start on replaced absolutely-positioned boxes, and as stretch on all other absolutely-positioned boxes.
• In table cell layouts, this keyword has no meaning as this property is ignored.
• In flexbox layouts, this keyword has no meaning as this property is ignored.
• In grid layouts, this keyword leads to a behavior similar to the one of stretch, except for boxes with an aspect ratio or an intrinsic sizes where it behaves like start.

start

The item is packed flush to each other toward the start edge of the alignment container in the appropriate axis.

end

The item is packed flush to each other toward the end edge of the alignment container in the appropriate axis.

flex-start

The item is packed flush to each other toward the edge of the alignment container depending on the flex container's main-start or cross-start side.
This only applies to flex layout items. For items that are not children of a flex container, this value is treated like start.

flex-end

The item is packed flush to each other toward the edge of the alignment container depending on the flex container's main-end or cross-end side.
This only applies to flex layout items. For items that are not children of a flex container, this value is treated like end.

self-start

The item is packed flush to the edge of the alignment container of the start side of the item, in the appropriate axis.

self-end

The item is packed flush to the edge of the alignment container of the end side of the item, in the appropriate axis.

center

The items are packed flush to each other toward the center of the of the alignment container.

left

The items are packed flush to each other toward the left edge of the alignment container. If the property’s axis is not parallel with the inline axis, this value behaves like start.

right

The items are packed flush to each other toward the right edge of the alignment container in the appropriate axis. If the property’s axis is not parallel with the inline axis, this value behaves like start.

baseline
first baseline
last baseline

Specifies participation in first- or last-baseline alignment: aligns the alignment baseline of the box’s first or last baseline set with the corresponding baseline in the shared first or last baseline set of all the boxes in its baseline-sharing group.
The fallback alignment for first baseline is start, the one for last baseline is end.

stretch

If the combined size of the items is less than the size of the alignment container, any auto-sized items have their size increased equally (not proportionally), while still respecting the constraints imposed by max-height/max-width (or equivalent functionality), so that the combined size exactly fills the alignment container.

Formal definition

Formal syntax

<'align-items'> <'justify-items'>?

Examples

Placing items in a flex container

div > div {
  box-sizing: border-box;
  border: 2px solid #8c8c8c;
  width: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
}

#item1 {
  background-color: #8cffa0;
  min-height: 30px;
}

#item2 {
  background-color: #a0c8ff;
  min-height: 50px;
}

#item3 {
  background-color: #ffa08c;
  min-height: 40px;
}

#item4 {
  background-color: #ffff8c;
  min-height: 60px;
}

#item5 {
  background-color: #ff8cff;
  min-height: 70px;
}

#item6 {
  background-color: #8cffff;
  min-height: 50px;
  font-size: 30px;
}

select {
  font-size: 16px;
}

.row {
  margin-top: 10px;
}

HTML

<div id="container" class="flex">
  <div id="item1">1</div>
  <div id="item2">2</div>
  <div id="item3">3</div>
  <div id="item4">4</div>
  <div id="item5">5</div>
  <div id="item6">6</div>
</div>

<div class="row">
  <label for="display">display: </label>
  <select id="display">
    <option value="flex">flex</option>
    <option value="grid">grid</option>
  </select>
</div>

<div class="row">
  <label for="values">place-items: </label>
  <select id="values">
    <option value="start">start</option>
    <option value="center">center</option>
    <option value="end">end</option>
    <option value="left">left</option>
    <option value="right">right</option>
    <option value="auto center">auto center</option>
    <option value="normal start">normal start</option>
    <option value="center normal">center normal</option>
    <option value="start auto">start auto</option>
    <option value="end normal">end normal</option>
    <option value="self-start auto">self-start auto</option>
    <option value="self-end normal">self-end normal</option>
    <option value="flex-start auto">flex-start auto</option>
    <option value="flex-end normal">flex-end normal</option>
    <option value="left auto">left auto</option>
    <option value="right normal">right normal</option>
    <option value="baseline normal">baseline normal</option>
    <option value="first baseline auto">first baseline auto</option>
    <option value="last baseline normal">last baseline normal</option>
    <option value="stretch auto">stretch auto</option>
  </select>
</div>

JavaScript

var values = document.getElementById('values');
var display = document.getElementById('display');
var container = document.getElementById('container');

values.addEventListener('change', function (evt) {
  container.style.placeItems = evt.target.value;
});

display.addEventListener('change', function (evt) {
  container.className = evt.target.value;
});

CSS

#container {
  height:200px;
  width: 240px;
  place-items: center; /* You can change this value by selecting another option in the list */
  background-color: #8c8c8c;
}

.flex {
  display: flex;
  flex-wrap: wrap;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, 50px);
}

Result

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• CSS Flexbox Guide: Basic Concepts of Flexbox
• CSS Flexbox Guide: Aligning items in a flex container
• CSS Grid Guide: Box alignment in CSS Grid layouts
• CSS Box Alignment
• The align-items property
• The align-self property
• The justify-items property
• The justify-self property