伪元素没有显示？

Question

我想在一些表单字段的末尾添加一个帮助徽标,打开工具提示.

一切正常,但.helptip图标(http://img1.wsimg.com/shared/img/1/small-help-icon.gif)左侧(合并)文本.我实际上想要在span文本的右边,所以我做了.help-tip:after.但是根本没有任何东西出现.

你能发现什么是错的吗？

<div class="advancedSearchFormSelectField fclear">
<span id="view_format_mis" class="advancedSearchFormlabel help-tip"> Include Columns in Result Set </span>

<select class="advancedSearchFormSelectBox" id="filters_include_columns" multiple="multiple" name="filters[include_columns][]">

<option value="x">X</option>
<option value="y">Y</option>
<option value="z">Z</option>
</select>
</div>

<div class="advancedSearchFormSelectField fclear">
<span id="view_format_mis" class="advancedSearchFormlabel"> Sort Column </span>
<!--No help tip here -->    
<select class="advancedSearchFormSelectBox" id="filters_sort_columns" multiple="multiple" name="filters[sort_columns]">

<option value="a">A</option>
<option value="b">B</option>
<option value="c">C</option>
</select>
</div>

.help-tip {
/* Merged text at the moment. .help-tip:after not working */ 
    cursor: pointer;
    width: 10px;
    height: 10px;
    background-repeat: no-repeat;
    background-image: url("/assets/small-help-icon.gif");
}

.advancedSearchFormSelectField{
    width:300px;
    margin: 5px;
    height: 60px;
    float:left;
}

Answer 1

你现在似乎没有使用伪元素.试试这个设置.help-tip来.help-tip::after和给予是content: ""和display: inline-block:

.help-tip::after {
    content: "";
    display: inline-block;
    cursor: pointer;
    width: 10px;
    height: 10px;
    background-repeat: no-repeat;
    background-image: url("/assets/small-help-icon.gif");
}