Horizontally and vertically centers a child element within a parent element using flexbox.

<div class="flexbox-centering"><div class="child">Centered content.</div></div>

.flexbox-centering {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100px;
}

Explanation

1. display: flex enables flexbox.
2. justify-content: center centers the child horizontally.
3. align-items: center centers the child vertically.

Browser support

⚠️ Needs prefixes for full support.

• https://caniuse.com/#feat=flexbox