how to align vertically in css code example

Example 1: css align items vertical center

.parent {
  display: flex;
  justify-content: center;
  align-items: center;
}

Example 2: css vertical center

/* No Flexbox */
.parent {
  position: relative;
}
.child {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
}

/* With Flexbox */

.parent {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

Example 3: center with css

.parent {
  position: relative;
}
.child {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

Example 4: css center

// example 1 
div { display: grid; place-items: center; }

// example 3
div{ display:flex; align-items:center; }

// example 3
div { width: 100%; margin: 0 auto; }

Example 5: css center div

<!-- 
	 Simple CSS CENTER DIV Example
 	 
	 * See Fiddle in link for PoC *
-->

<div class="parent">
  <div class="child">
    <p>
      Eh Up Me Duck!
    </p>
  </div>
</div>

<style>
.parent {
  /* Just for aesthetics: see fiddle */
  border: 1px solid black;
  padding: 2px;
}

.child {
  border: 1px solid red;
  width: 50%;
  
  /* This is where the magic happens */
  margin-left: auto;
  margin-right: auto;
  /**********************************/
}

p {
  /* As you do */
  text-align: center;
}
</style>

Example 6: vertical align div

HTML:
<div class="ext-box">
	<div class="int-box">
		<h2>Some txt</h2>
		<p>bla bla bla</p>
	</div>
</div>

CSS:
div.ext-box { display: table; height: 100%; width:100%;}
div.int-box { display: table-cell; vertical-align: middle; }