div边框四个角样式（个人笔记）

background:
		linear-gradient(to left, #263d72, #263d72) left top no-repeat,
		linear-gradient(to bottom, #263d72, #263d72) left top no-repeat,
		linear-gradient(to left, #263d72, #263d72) right top no-repeat,
		linear-gradient(to bottom, #263d72, #263d72) right top no-repeat,
		linear-gradient(to left, #263d72, #263d72) left bottom no-repeat,
		linear-gradient(to bottom, #263d72, #263d72) left bottom no-repeat,
		linear-gradient(to left, #263d72, #263d72) right bottom no-repeat,
		linear-gradient(to left, #263d72, #263d72) right bottom no-repeat;
	background-size: 2px 20px, 20px 2px, 2px 20px, 20px 2px, 2px 20px, 20px 2px, 2px 20px, 20px 2px;