css solves the effect of overriding the transparency of parent elements
CSS-compatible browser transparency writing method
1.{opacity:0.3;filter:alpha(opacity=30);}
CSS is not compatible with overlay transparency. If the parent element has transparency set, then the child element cannot be more transparent than the parent element, so you can use the following methods to achieve similar effects.
1.<div id="bgttt" style="opacity:0.3;filter:alpha(opacity=30);position:absolute;left:0;top:0; background:#000;width:100%;height:20px ;font-size:12px"></div> <div id="showttt" style="position:absolute;left:0;top:0px; width:100%;height:20px;z-index:10;text-align:center"></div>