浏览器的兼容模式下的button中文字垂直方向不居中显示

<span style="color: #0000ff;"><span style="color: #800000;">button </span><span style="color: #ff0000;">style</span><span style="color: #0000ff;">="cursor:pointer;vertical-align: middle;"</span> <span style="color: #0000ff;">></span>删除<span style="color: #0000ff;"></span><span style="color: #800000;">button</span><span style="color: #0000ff;">></span></span>

<span style="color: #0000ff;"><span style="color: #800000;">button </span><span style="color: #ff0000;">style</span><span style="color: #0000ff;">="cursor:pointer;vertical-align: middle;<span style="color: #ff0000;"><strong>height</strong></span>:21px;"</span> <span style="color: #0000ff;">></span>删除<span style="color: #0000ff;"></span><span style="color: #800000;">button</span><span style="color: #0000ff;">></span></span>