Flex center / center vertical
.flex-container {
display: -ms-flexbox;
display: -webkit-flex;
display: flex;
-webkit-flex-direction: row;
-ms-flex-direction: row;
flex-direction: row;
-webkit-flex-wrap: nowrap;
-ms-flex-wrap: nowrap;
flex-wrap: nowrap;
-webkit-justify-content: flex-start;
-ms-flex-pack: start;
justify-content: flex-start;
-webkit-align-content: stretch;
-ms-flex-line-pack: stretch;
align-content: stretch;
-webkit-align-items: center;
-ms-flex-align: center;
align-items: center;
}
.flex-item:nth-child(1) {
-webkit-order: 0;
-ms-flex-order: 0;
order: 0;
-webkit-flex: 0 1 auto;
-ms-flex: 0 1 auto;
flex: 0 1 auto;
-webkit-align-self: auto;
-ms-flex-item-align: auto;
align-self: auto;
}