align-items

The interactive example below demonstrates some of the values for align-items using grid and flex layout.

normal

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

• In absolutely-positioned layouts, the keyword behaves like start on replaced absolutely-positioned boxes, and as stretch on all other absolutely-positioned boxes.
• In static position of absolutely-positioned layouts, the keyword behaves as stretch.
• For flex items, the keyword behaves as stretch.
• For grid items, 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.
• The property doesn't apply to block-level boxes, and to table cells.

center

The flex items' margin boxes are centered within the line on the cross-axis. If the cross-size of an item is larger than the flex container, it will overflow equally in both directions.

start

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

end

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

self-start

The items are packed flush to the edge of the alignment container's start side of the item, in the appropriate axis.

self-end

The items are packed flush to the edge of the alignment container's end side of the item, in the appropriate axis.

baseline, first baseline, last baseline

All flex items are aligned such that their flex container baselines align. The item with the largest distance between its cross-start margin edge and its baseline is flushed with the cross-start edge of the line.

stretch

If the items are smaller than the alignment container, auto-sized items will be equally enlarged to fill the container, respecting the items' width and height limits.

anchor-center Experimental

In the case of anchor-positioned elements, aligns the items to the center of the associated anchor element in the block direction. See Centering on the anchor using anchor-center.

safe

Used alongside an alignment keyword. If the chosen keyword means that the item overflows the alignment container causing data loss, the item is instead aligned as if the alignment mode were start.

unsafe

Used alongside an alignment keyword. Regardless of the relative sizes of the item and alignment container and whether overflow which causes data loss might happen, the given alignment value is honored.

There are also two values that were defined for flexbox, as they are base on flex model axes concepts, that work in grid layouts as well:

flex-start

Used in flex layout only, aligns the flex items flush against the flex container's main-start or cross-start side. When used outside of a flex formatting context, this value behaves as start.

flex-end

Used in flex layout only, aligns the flex items flush against the flex container's main-end or cross-end side. When used outside of a flex formatting context, this value behaves as end.

align-items = 
  normal                                    |
  stretch                                   |
  <baseline-position>                       |
  [ <overflow-position>? <self-position> ]  |
  anchor-center                             

<baseline-position> = 
  [ first | last ]?  &&
  baseline           

<overflow-position> = 
  unsafe  |
  safe    

<self-position> = 
  center      |
  start       |
  end         |
  self-start  |
  self-end    |
  flex-start  |
  flex-end    

In this example we have a container with six children. A <select> dropdown menu enables toggling the display of the container between grid and flex. A second menu enables changing the value of the container's align-items property.

We style a the container and items in a manner that ensures we have two lines or rows or items. We defined .flex and .grid classes, which will be applied to the container with JavaScript. They set the display value of the container, and change its background and border colors providing an additional indicator that the layout has changed. The six flex items each have a different background color, with the 4th item being two lines long and the 6th item having an enlarged font.

.flex,
.grid {
  height: 200px;
  width: 500px;
  align-items: initial; /* Change the value in the live sample */
  border: solid 5px transparent;
  gap: 3px;
}

.flex {
  display: flex;
  flex-wrap: wrap;
  background-color: #8c8c9f;
  border-color: magenta;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, 100px);
  background-color: #9f8c8c;
  border-color: slateblue;
}

#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;
}

div > div {
  box-sizing: border-box;
  border: 2px solid #fff;
  width: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
}

We include a container <div> with six nested <div> children. The HTML for the form and the JavaScript that changes the container's class have been hidden for the sake of brevity.

<div id="container" class="flex">
  <div id="item1">1</div>
  <div id="item2">2</div>
  <div id="item3">3</div>
  <div id="item4">4<br />line 2</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">align-items: </label>
  <select id="values">
    <option value="normal">normal</option>
    <option value="flex-start">flex-start</option>
    <option value="flex-end">flex-end</option>
    <option value="center" selected>center</option>
    <option value="baseline">baseline</option>
    <option value="stretch">stretch</option>

    <option value="start">start</option>
    <option value="end">end</option>
    <option value="self-start">self-start</option>
    <option value="self-end">self-end</option>

    <option value="first baseline">first baseline</option>
    <option value="last baseline">last baseline</option>

    <option value="safe center">safe center</option>
    <option value="unsafe center">unsafe center</option>
    <option value="safe right">safe right</option>
    <option value="unsafe right">unsafe right</option>
    <option value="safe end">safe end</option>
    <option value="unsafe end">unsafe end</option>
    <option value="safe self-end">safe self-end</option>
    <option value="unsafe self-end">unsafe self-end</option>
    <option value="safe flex-end">safe flex-end</option>
    <option value="unsafe flex-end">unsafe flex-end</option>
  </select>
</div>

const values = document.getElementById("values");
const display = document.getElementById("display");
const container = document.getElementById("container");

values.addEventListener("change", (evt) => {
  container.style.alignItems = evt.target.value;
});

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

• align-self
• align-content
• justify-items
• place-items shorthand
• Basic concepts of flexbox
• Aligning items in a flex container
• Box alignment in CSS grid layouts
• CSS box alignment module
• CSS flexible box layout module
• CSS grid layout module