Good day.
I am using Subgurim library for displaing google maps in EO Splitter. Splitter docs contains example with event OnSplitterResized() to riseze content of panel. For example:

function OnSplitterResized(splitter)
{
//Get the left pane's client size
var w = splitter.getRightPane().getWidth();
var h = splitter.getRightPane().getHeight();

//Resize the text box
var button = document.getElementById("<%=btnSearch.ClientID%>");
var textBox = document.getElementById("<%=txtKeyword.ClientID%>");
var textBoxWidth = w - button.offsetWidth - 20;
if (textBoxWidth < 50)
textBoxWidth = 50;
textBox.style.width = textBoxWidth.toString() + "px";

//Resize the TreeView
var treeView = eo_GetObject("TreeView1");
treeView.setSize(w - 16, h - 46);
}

How can I resize this? ->

<cc1:GMap ID="BigGMap" runat="server"
Key="ABQIAAAAguZIrT4Nv0X9sQTPiLhIRBSThBTgI-"
enableGKeyboardHandler="True" enableHookMouseWheelToZoom="True"
enablePostBackPersistence="True" enableServerEvents="True" GZoom="10"
Language="ru" Height="" Width="" />

I tried like that

var gmap = document.getElementById('<%=BigGMap.ClientID%>');
gmap.getAttribute('Height') = splitter.getRightPane().getHeight() + "px";

but its 'null'. (I am a beginner in web)

Thanks for explanation.