css水平垂直居中

flex

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

或者直接

.parent {
	display: flex;
}
.child {
	margin: auto;
}

table

.parent {
	display: table;
	text-align: center;
}
.child {
	display: table-cell;
	vertical-align: middle;
}