仿照Bootstrap的input 修改 upload上传图片的样式

html：

<div?class="form-group">
????<label?class="col-sm-3?col-sm-6?control-label">图片</label>
????<span?class="problem-must">?</span>
????<div?class="col-sm-8">
????????<a?class="fb-upload"?href="javascript:void(0);">?
????????????<input?class="form-control"?name="pic"?type="file"?accept=".gif,.jpg,.png,.jpeg"?/>?
????????????<span?class="fb-img">上传图片</span>
	</a>
????</div>
</div>

css:

.form-group?input[type="file"]?{
????cursor:?pointer;
????opacity:?0;
????position:?absolute;
????top:?0;
}
.fb-img?{
????border:?1px?solid?#ccc;
????border-radius:?4px;
????box-shadow:?0?1px?1px?rgba(0,?0,?0.075)?inset;
????color:?gray;
????display:?inline-block;
????height:?34px;
????line-height:?1.42857;
????padding:?6px?12px;
????text-align:?left;
????transition:?border-color?0.15s?ease-in-out?0s,?box-shadow?0.15s?ease-in-out?0s;
????width:?100%;
}