html - Why are flex items not wrapping?

Question

I am attempting to make multiple rows of squares (3 per line) which have the same height.

I have written some HTML and CSS for this but the boxes all go on the same line.

Here's what I have so far:

#list-wrapper {
  display: flex;
  width: 100%;
}
#list-wrapper div {
  width: 33.33%;
}
#list-wrapper div img {
  flex: 1;
}

<div id="list-wrapper">
  <div>
    <img src="images/1.png" alt="image one" />
  </div>
  <div>
    <img src="images/2.png" alt="image two" />
  </div>
  <div>
    <img src="images/1.png" alt="image one" />
  </div>
  <div>
    <img src="images/2.png" alt="image two" />
  </div>
  <div>
    <img src="images/1.png" alt="image one" />
  </div>
  <div>
    <img src="images/2.png" alt="image two" />
  </div>
</div>

Answer 1

An initial setting of a flex container is flex-wrap: nowrap.

This means that when you create a flex container (by applying display: flex or display: inline-flex to an element) all child elements ("flex items") are confined to a single line.

To enable flex items to wrap use flex-wrap: wrap.

---

Here are a few examples of how flex properties work:

A simple flex container with various flex items containing an image:

#list-wrapper {
    display: flex;
    border: 1px solid black;
}

#list-wrapper div {}

#list-wrapper div img {
    height: 150px;
    width: 150px;
}

<div id="list-wrapper">
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
    <div><img src="http://i.imgur.com/60PVLis.png" alt=""></div>
</div>