inline-block 导致元素下沉 解决方法添加vertical-align:middle属性

<div class="layui-input-block">
<input name="username" lay-verify="required" autocomplete="off" id="user" placeholder="请输入用户名" class="layui-input" type="text">
<span class="error success"></span>
</div>

.success {
    background: url(../images/right01.png) 0 bottom no-repeat;
     30px;
    height: 30px;
    display: inline-block;
}

.success {
    background: url(../images/right01.png) 0 bottom no-repeat;
     30px;
    height: 30px;
    display: inline-block;
    vertical-align:middle;      
}