<div style="filter:alpha(opacity=50);background:#ffffff;width:600;"> <span style="color:yellow">图层背景半透明，字体颜色也半透明</span></div><div style="filter:alpha(opacity=50);background:#ffffff;width:600"> <span style="position:relative;color:yellow">图层背景半透明，字体颜色不半透明</span></div>
