align div vertically middle, center, middle

center.css

/* fallback for non-Flexbox browsers */
display: inline-block;

/* Flexbox browsers */
display: -webkit-inline-box;
display: -moz-inline-box;
display: -ms-inline-flexbox;
display: -webkit-inline-flex;
display: inline-flex;

/* vertical centering for legacy, horizontal centering for modern */
-webkit-box-pack: center;
-moz-box-pack: center;
-ms-flex-pack: center;
-webkit-justify-content: center;
justify-content: center;

/* modern Flexbox only */
-ms-flex-align: center;
-webkit-align-items: center;
align-items: center;

/* legacy Flexbox only */
-webkit-box-orient: vertical;
-moz-box-orient: vertical;