if ((screen.width >= "800") && (screen.width < "1024")) 
  {document.write("<link href='app/base_800.css' rel='stylesheet' type='text/css' />");  }

 if ((screen.width >= "1024") && (screen.width < "1152")) 
   {document.write("<link href='app/base_1024.css' rel='stylesheet' type='text/css' />");  }

 if ((screen.width >= "1152") && (screen.width < "1280")) 
   {document.write("<link href='app/base_1152.css' rel='stylesheet' type='text/css' />");  }

 if ((screen.width >= "1280") && (screen.width < "1360")) 
   {document.write("<link href='app/base_1280.css' rel='stylesheet' type='text/css' />");  }

 if ((screen.width >= "1360") && (screen.width < "1600"))
   { document.write("<link href='app/base_1366.css' rel='stylesheet' type='text/css' />");  }
   
 if ((screen.width >= "1600") && (screen.width < "1900"))
   {document.write("<link href='app/base_1600.css' rel='stylesheet' type='text/css' />");  }
   
 if ((screen.width >="1900") && (screen.width < "2500"))
   {document.write("<link href='app/base_1900.css' rel='stylesheet' type='text/css' />");  }