order

In the above demo, select the options on the left-hand side to change the value of the purple box's order property. The blue boxes have been given fixed order values.

Bear in mind the effect of source order. When order: 2; is selected for example, the purple box is placed before the two blue boxes with order: 2;. This is because the purple box appears before the blue boxes in the source code.

/* <integer> values */
order: 5;
order: -5;

/* Global values */
order: inherit;
order: initial;
order: revert;
order: revert-layer;
order: unset;

Since order is only meant to affect the visual order of elements and not their logical or tab order. order must not be used on non-visual media such as speech.

<integer>

Represents the ordinal group to be used by the item.

Using the order property will create a disconnect between the visual presentation of content and DOM order. This will adversely affect users experiencing low vision navigating with the aid of assistive technology such as a screen reader. If the visual (css) order is important, then screen reader users will not have access to the correct reading order.

• Flexbox & the keyboard navigation disconnect — Tink
• Source Order Matters | Adrian Roselli
• MDN Understanding WCAG, Guideline 1.3 explanations
• Understanding Success Criterion 1.3.2 | W3C Understanding WCAG 2.0

order = 
  <integer>  

This example uses CSS to create a classic two-sidebar layout surrounding a content block. The Flexible Box Layout Module automatically creates blocks of equal vertical size and uses as much horizontal space as available.

HTML

<header>…</header>
<main>
  <article>Article</article>
  <nav>Nav</nav>
  <aside>Aside</aside>
</main>
<footer>…</footer>

CSS

main {
  display: flex;
  text-align: center;
}
main > article {
  flex: 1;
  order: 2;
}
main > nav {
  width: 200px;
  order: 1;
}
main > aside {
  width: 200px;
  order: 3;
}

Result

• CSS Flexbox Guide: Basic Concepts of Flexbox
• CSS Flexbox Guide: Ordering flex items
• CSS Grid Guide: CSS Grid Layout and accessibility