用css给宽高不固定的矩形画对角线

.kong{
			width: 200rpx;
			height: 76rpx;
			 background:  linear-gradient(
					to bottom right, #E5E5E5 0%, rgba(0, 0, 0, 0.1) calc(50% - 1px),
					#175CFF 50%, rgba(0, 0, 0, 0.1) calc(50% + 1px),
					rgba(0, 0, 0, 0.1) 100%
			 );
	}

参考：
https://blog.csdn.net/weixin_38779534/article/details/104778147