a_gold1

<div class="square">
	<div class="square1">45</div>
</div>

.square {
  	height: 150px;
  	width: 150px;
  	background: #ccc;

	display: flex;
	flex-direction: row;
	flex-wrap: nowrap;
	justify-content: center;
	align-items: center;
	align-content: stretch;

  }
  .square1 {
  	background: orange;
  	width: 90px;
  	height: 90px;
  	-o-transform: rotate(45deg);
	-ms-transform: rotate(45deg);
	-moz-transform: rotate(45deg);
	-webkit-transform: rotate(45deg);
	transform: rotate(45deg);

	display: flex;
	flex-direction: row;
	flex-wrap: nowrap;
	justify-content: center;
	align-items: center;
	align-content: stretch;
  }