Answers for "align divs vertically"

css center

/* this will center all children within the parent element. */
.parent {
  display: flex;
  justify-content: center; /* horizontal */
  align-items: center; /* vertical */
}

css vertical align

.top-align {
	vertical-align: top;
}  

.center-align {
  	vertical-align: middle;
}

vertical align into div

#parent {position: relative;}

#child {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    width: 50%;
    height: 30%;
    margin: auto;
}

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; }