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<h4>默认 stretch</h4>
<ul>
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
</ul>

<h4>flex-start</h4>
<ul id="second">
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
</ul>

<h4>flex-end</h4>
<ul id="third">
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
</ul>

<h4>flex-end</h4>
<ul id="forth">
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
</ul>

<h4>base-line</h4>
<ul id="fifth">
  <li>x</li>
  <li>hello base line </li>
  <li>3</li>
  <li>4</li>
</ul>

ul {
  display: flex;
  width: 400px;
  height: 80px;
  padding: 4px;
  border: 1px solid #ddd;
}
li {
  width: 50px;
  list-style:none;
  border: 1px solid #ddd;
  background: #eee;
}
li + li {
  margin-left: 10px;
}

ul#second{
  align-items: flex-start;
}

ul#third {
  align-items: flex-end;
}

ul#forth {
  align-items: center;
}

ul#fifth {
  align-items: baseline;
}