want to decrease the size of the div which is added in dialog

I am added div content into the dialog box using jquery.I am using the same div content to display in my page.Now i want to decrease the size of content by percentage which i am pushing in dialog.But it should apply only for the content of dialog not for the content on my page.So how can i do that using jquery?help me

$(function() {
        $( "#maincontainer" ).dialog({
            autoOpen: false,
            widt开发者_运维问答h:50%,
            height:400,
            autoClose: false,
            show: "fold",
            hide: "core"
        });

        $( "#previewBtn").click(function() {
            $( "#maincontainer" ).dialog( "open" );
            return false;
        });
});

you 'height:auto' property; this may work