console 命令行工具 X clear
console
<html>

<head></head>
<style>
    .main{
        height:500px;
        width:100%;
        background-color:red;
    }
	.container {
        width:100%;
        height:100%;
		display: flex;
		justify-content: flex-end;
        align-items:center;
        background-color:green;
		/* 项目朝主轴末端对齐 */
	}

	.item {
		width: 300px;
		height: 200px;
		background-color: #ccc;
		margin: 5px;
	}
</style>

<body>
	<div class='main'>
		<div class="container">
			<div class="item">Item 1</div>
		</div>
	</div>

</body>

</html>