Height of ContentPlaceHolder in master page According to Screen resolution

[Mangesh]

I am using Telerik Controls in Master page.I am facing a problem regrading panel height.Whenever scren size changes then panel height automatically reduce or increase.it should be increase according to Screen resolution.Please provide me solution so that i can use Telerik Controls.

For Example ..

Currently i am using Following code to adjust Panel Height

var div=document.getElementById("ctl00_divWidth");
alert(div);
   if ( (screen.width == 1280) && (screen.height == 1024) ) //1280 x 1024
        divWidth = 1270;
    else if ( (screen.width == 1152) && (screen.height == 864) )  //1152 x 864
        divWidth = 1142;
    else if ( (screen.width == 1024) && (screen.height == 768) )  //1024 x 768
        divWidth = 1015;
    else if ( (screen.width == 1024) && (screen.height == 768) )  //1024 x 768
        divWidth = 1015;
    else if ( (screen.width == 1024) && (screen.height == 768) )  //1024 x 768
    divWidth = 1015;
    else if ( (screen.width == 1024) && (screen.height == 768) )  //1024 x 768
    divWidth = 1015;
    else if ( (screen.width == 1024) && (screen.height == 768) )  //1024 x 768
    divWidth = 1015;
    else if ( (screen.width == 1024) && (screen.height == 768) )  //1024 x 768
    divWidth = 1015;
    else if ( (screen.width == 1024) && (screen.height == 768) )  //1024 x 768
    divWidth = 1015;
    else if ( (screen.width == 1024) && (screen.height == 768) )  //1024 x 768
    divWidth = 1015;
    else if ( (screen.width == 1024) && (screen.height == 768) )  //1024 x 768
    divWidth = 1015;

Above code is not working properly.Please resolve my problem..