Share the learning summary of Media Queries in CSS3

<link rel="stylesheet" media="all" href="style.css" />   
<link rel="stylesheet" media="screen and (min-width:980px)" href="desktop.css" />   
<link rel="stylesheet" media="screen and (min-width:768px) and (max-width:980px)" href="pad.css" />   
<link rel="stylesheet" media="screen and (min-width:480) and (max-width: 768px)" href="phone.css" />   
<link rel="stylesheet" media="screen and (max-width:320px)" href="small.css" />

@media screen and (min-width: 980px) {   
    //css code
}   
@screen and (min-width:768px) and (max-width:980px) {   
    //css code
}   
@screen and (min-width:480) and (max-width: 768px) {   
    //css code
}   
@screen and (max-width:320px) {   
    //css code
}   

@media screen and (max-device-width: 480px) {   
    //max-device-width等于480px
}   
@media screen and (device-aspect-ratio: 16/9), screen and (device-aspect-ratio: 16/10) {   
    //设备宽高比   
}   
@media all and (orientation:portrait) {   
    //竖屏   
}   
@media all and (orientation:landscape) {   
    //横屏   
}

@media screen and (max-width: 900px) {   
  ...   
}

<!--[if lt IE 9]>
    <script src="http://css3-mediaqueries-js.googlecode.com/svn/trunk/css3-mediaqueries.js"></script>
<![endif]-->

/*Adjust the layout in IE8 and lower than IE8 when the browser is narrow*/
function processLowerIENavigate()   
{   
   var isIE = document.all ? 1 : 0;   
   if (isIE == 1)   
   {   
       if(navigator.userAgent.indexOf("MSIE7.0") > 0 || navigator.userAgent.indexOf("MSIE 8.0") > 0)   
       {     
    //  var doc=document; 
           var link=document.createElement("link");   
           link.setAttribute("rel", "stylesheet");   
           link.setAttribute("type", "text/css");   
           link.setAttribute("id", "size-stylesheet");   
           link.setAttribute("href", "");   

           var heads = document.getElementsByTagName("head");   
           if(heads.length)   
               heads[0].appendChild(link);   
           else
               document.documentElement.appendChild(link);   

           document.write("<script type=&#39;text/javascript&#39; src=&#39;jquery.min.js&#39;></script>");   
           document.write("<script type=&#39;text/javascript&#39; src=&#39;media_screen.js&#39;></script>");   

       }   
   }    
}   
var lowerIE8 = processLowerIENavigate();   

media_screen.js文件内容如下，直接从网上copy：   
function adjustStyle(width) {   
    width = parseInt(width);   
    if (width < 902) {   
//alert("<900");
//alert(width);
        $("#size-stylesheet").attr("href", "navigateLowerIE8.css");   
    } else {   
      // alert(">900");
  //alert(width);
       $("#size-stylesheet").attr("href", "");    
    }   
}   

$(function() {   
    adjustStyle($(this).width());   
    $(window).resize(function() {   
        adjustStyle($(this).width());   
    });   
});