<ul class="flex-container flex-start">
  <li class="flex-item">1</li>
  <li class="flex-item">2</li>
  <li class="flex-item">3</li>
  <li class="flex-item">4</li>
  <li class="flex-item">5</li>
  <li class="flex-item">6</li>
</ul>

<ul class="flex-container flex-end">
  <li class="flex-item">1</li>
  <li class="flex-item">2</li>
  <li class="flex-item">3</li>
  <li class="flex-item">4</li>
  <li class="flex-item">5</li>
  <li class="flex-item">6</li>
</ul>

<ul class="flex-container center">
  <li class="flex-item">1</li>
  <li class="flex-item">2</li>
  <li class="flex-item">3</li>
  <li class="flex-item">4</li>
  <li class="flex-item">5</li>
  <li class="flex-item">6</li>
</ul>

<ul class="flex-container space-between">
  <li class="flex-item">1</li>
  <li class="flex-item">2</li>
  <li class="flex-item">3</li>
  <li class="flex-item">4</li>
  <li class="flex-item">5</li>
  <li class="flex-item">6</li>
</ul>

<ul class="flex-container space-around">
  <li class="flex-item">1</li>
  <li class="flex-item">2</li>
  <li class="flex-item">3</li>
  <li class="flex-item">4</li>
  <li class="flex-item">5</li>
  <li class="flex-item">6</li>
</ul>

<ul class="flex-container stretch">
  <li class="flex-item">1</li>
  <li class="flex-item">2</li>
  <li class="flex-item">3</li>
  <li class="flex-item">4</li>
  <li class="flex-item">5</li>
  <li class="flex-item">6</li>
</ul>

.flex-container {
  padding: 0;
  margin: 0;
  list-style: none;
  float: left;
  width: 120px;
  height: 300px;
  padding: 10px;
  border: 1px solid silver;
  margin-top: 10px;
  
  -ms-box-orient: horizontal;
  display: -webkit-box;
  display: -moz-box;
  display: -ms-flexbox;
  display: -moz-flex;
  display: -webkit-flex;
  display: flex;
  
  -webkit-flex-flow: row wrap;
  flex-flow: row wrap;
}

.flex-start { 
  -webkit-align-content: flex-start; 
  align-content: flex-start; 
}

.flex-end { 
  -webkit-align-content: flex-end; 
  align-content: flex-end; 
}
.flex-end li {
  background: gold;
}

.center { 
  -webkit-align-content: center; 
  align-content: center; 
}
.center li {
  background: deepskyblue;
}

.space-between { 
  -webkit-align-content: space-between; 
  align-content: space-between; 
}  
.space-between li {
  background: lightgreen;
}

.space-around { 
  -webkit-align-content: space-around; 
  align-content: space-around; 
}
.space-around li {
  background: hotpink;
}

.stretch { 
  -webkit-align-content: stretch; 
  align-content: stretch; 
}
.stretch li {
  background: chocolate;
}

.flex-item {
  background: tomato;
  padding: 5px;
  width: 50px;
  height: 50px;
  
  line-height: 50px;
  color: white;
  font-weight: bold;
  font-size: 2em;
  text-align: center;
}