css - flexbox space-between and align right

Question

I have a div with 1 to 3 items and I want them to behave like this :

1. Three items : take the whole line with justify-content: space-between

   +-----------+
   | 1 | 2 | 3 |
   +-----------+
   

2. If there is only 1 item, align it to the right.

   +-----------+
   |       | 3 |
   +-----------+
   

Here's my code :

.container {
  display: flex;
  width: 300px;
  justify-content: space-between;
  /* Styling only */
  padding: 10px;
  background: #ccc;
  margin-bottom: 10px;
}
.container div {
  /* Styling only */
  background: white;
  padding: 20px 40px;
  width: 10px;
}

<div class="container">
  <div>
    1
  </div>
  <div>
    2
  </div>
  <div>
    3
  </div>
</div>

<div class="container">
  <div>
    3
  </div>
</div>

question from:https://stackoverflow.com/questions/33278246/flexbox-space-between-and-align-right

Answer 1

There is a selector for that.

.container div:only-child {
  margin-left: auto;
}

.container {
  display: flex;
  width: 300px;
  justify-content: space-between;
  /* Styling only */
  padding: 10px;
  background: #ccc;
  margin-bottom: 10px;
}
.container div {
  /* Styling only */
  background: white;
  padding: 20px 40px;
  width: 10px;
}
.container div:only-child {
  align-self: flex-end;
  margin-left: auto;
}

<div class="container">
  <div>
    1
  </div>
  <div>
    2
  </div>
  <div>
    3
  </div>
</div>

<div class="container">
  <div>
    3
  </div>
</div>