How does css make nested div layers not inherit the transparency of the parent div layer?

Http://zhidao.baidu.com/link?url=cvQhh0Q7_ah0qg9tc-2zP0cjB_ Poiiiq6t6rfpp4azppnovjuqyy7tt41tu5pwzrtryimnckdmkav36or-rrafyyghs__ulnjlnioggkyoc How does css make nested div layers not inherit the transparency of the parent div layer? http://blog.csdn.net/foart/article/details/39177653 Div floats on top and makes div background Translucent Code http://xiaohuang.cc/post/282.html/HTTP// Www.w3school.com.cn/css/css_image_transparency.asp

<style media= "Screen" >
. yss{
width:200px;
height:200px;

}
. ys{
width:200px;
height:200px;
/*background-size:200px 200px;*/
/*background:url ('/images/logosmall.jpg '); * *

Background:url (' @picstr ');
background-position:50% 50%;
Background-repeat:no-repeat;
background-size:200px 200px;

}
. kss{
width:200px;
height:200px;
/*background:url ('/images/logosmall.jpg '); * *
/*background-size:200px 200px;*/
Background:url (' @picstr ');
background-position:50% 50%;
Background-repeat:no-repeat;
background-size:200px 200px;
opacity:0.4;
Filter: "Alpha (opacity=40)";
-ms-filter: "Alpha (opacity=40)"; /* old version IE */

}
. edd{
width:200px;
height:200px;
border:0px solid black;
/*position:relative;*/
Position:absolute;
margin-top:-200px;
/*margin-left:-200px;*/
}

. svgks{
width:200px;
height:200px;
border:0px solid black;
/*position:relative;*/
Position:absolute;
margin-top:-200px;
/*margin-left:-200px;*/

opacity:0;
Filter: "Alpha (opacity=0)";
-ms-filter: "Alpha (opacity=0)"; /* old version IE */
}
</style>

@if (cwords! = null)
{
<input type= "hidden" name= "Svgid" id= "Svgid" value= "@ (cwords. Vectorgraphfile) "/>@*
<input type= "hidden" name= "Svgreset" id= "Svgreset" value= "0"/>


*@<p id= "PPP" class= "ys" style= "" >

</p>
<svg id= "svg" class= "edd" ></svg>

<p id= "Div3" style= "Display:none;" >
@* @ (Userhelper.getwotdtrext (cwords. Id, 2)) *@
@* Test One is two*@
@ (Userhelper.getwotdtrext (cwords. Id, 2))
</p>
<p> &nbsp; &nbsp; &nbsp;<input type= "button" id= "ANI" class= "btn btn-success btn-sm" value= "Play" onclick= "SS ();" />
<input type= "button" id= "Svgreset" class= "btn btn-success btn-sm" value= "reset" onclick= "resets ();" />
</p>

How does css make nested div layers not inherit the transparency of the parent div layer?