Position last flex item at the end of container

Question

This question concerns a browser with full css3 support including flexbox.

I have a flex container with some items in it. They are all justified to flex-start but I want the last .end item to be justified to flex-end. Is there a good way to do this without modifying the HTML and without resorting to absolute positioning?

Answer 1

Flexible Box Layout Module - 8.1. Aligning with auto margins

Auto margins on flex items have an effect very similar to auto margins in block flow:

• During calculations of flex bases and flexible lengths, auto margins are treated as 0.

• Prior to alignment via justify-content and align-self, any positive free space is distributed to auto margins in that dimension.

Therefore you could use margin-top: auto to distribute the space between the other elements and the last element.

This will position the last element at the bottom.

p:last-of-type {
  margin-top: auto;
}

.container {
  display: flex;
  flex-direction: column;
  border: 1px solid #000;
  min-height: 200px;
  width: 100px;
}
p {
  height: 30px;
  background-color: blue;
  margin: 5px;
}
p:last-of-type {
  margin-top: auto;
}

<div class="container">
  <p></p>
  <p></p>
  <p></p>
</div>

---

Likewise, you can also use margin-left: auto or margin-right: auto for the same alignment horizontally.

p:last-of-type {
  margin-left: auto;
}

.container {
  display: flex;
  width: 100%;
  border: 1px solid #000;
}
p {
  height: 50px;
  width: 50px;
  background-color: blue;
  margin: 5px;
}
p:last-of-type {
  margin-left: auto;
}

<div class="container">
  <p></p>
  <p></p>
  <p></p>
  <p></p>
</div>