自定义下拉框 支持模糊搜索 支持键盘上下选择

 .ldg-select {
	position:relative;
	display:inline-block;
}
.ldg-select-input {
	width:200px;
	padding:5px;
	border:1px solid #ccc;
	cursor:pointer;
}
.ldg-select-down {
	position:absolute;
	width:100%;
	max-height:200px;
	overflow-y:auto;
	border:1px solid #ccc;
	background-color:#fff;
	display:none;
}
.ldg-select-down>* {
	padding:5px;
	cursor:pointer;
}
.ldg-select-down>*:hover {
	background-color:#f2f2f2;
}
.ldg-select-down>*.selected {
	background-color:#ccc;
}