Flexbug: inline-block with flex children


In Internet Explorer 11 and Firefox 40, vertical alignment of inline-block elements is broken when one of those contains a flex element.
The workaround? Apply vertical-align: middle to the parent of the flex item.


Early flexbox implementations can be fairly buggy, across all browsers. A lot of issues are documented by Philip Walton in this comprehensive list of flexbugs and workarounds. The problem I encountered is not on that list, nor could I find any other bugs with a similar description.

Let’s say you have two UI components:


  • A hyperlink styled as a button.
  • Next to the hyperlink, a form with a single search field with a button added on.

The image above demonstrates the expected browser behaviour. Both the form and the link-button are styled with display: inline-block. Inside the form is a wrapper-div with display: flex, containing an icon and an input with flex: 1 0 auto. (The latter is a standard pattern to create input add-ons, as specified by Solved With Flexbox.)

However, Internet Explorer 11 and Firefox 40—perhaps other browsers as well—align the link-button partially below the search field:


Luckily, there’s a simple workaroud: apply vertical-align: middle to the parent of the flex item, in this case the form.

If you don’t like reading text and rather look at actual code, I created a stripped-down demo on CodePen.