how to center align code example

Example 1: align in the middle of page html

.centered {
  position: fixed;
  top: 50%;
  left: 50%;
  /* bring your own prefixes */
  transform: translate(-50%, -50%);
}

Example 2: center a div

<div id="outer">
  <div id="inner">Foo foo</div>
</div>
//css:, demo with border
<style>
#inner {
  display: table;
  margin: 0 auto;
  border: 1px solid black;
}

#outer {
  border: 1px solid red;
  width:100%
}
</style>