How to write code for NAV ,HTML Control and Data,Lable part for MSCRM using Xrm to UR12 compatible to multi browser ?

I am writting code for UR12 compatible to multi browser

I am using below code to hide Process in CRM using document.getElementById , but i want Xrm code to hide this , how to do that?

if (document.getElementById("_NA_PROC") != null)
document.getElementById("_NA_PROC").style.display = "none";


-------------------------------


I am using below code to hide HTML button on CRM using document.getElementById , but i want Xrm code to hide this , how to do that?
Will get this HTML id in Xrm ? is that possible?

if( document.getElementById('CustomhtmlButtononCRM') != null)
{
   document.getElementById('CustomhtmlButtononCRM').style.display = displayType;
}

----------------------------------------

I have a contol crm control 'letterlabel' on crm form , and want hide it's data part and chnage it's text part with
It works for document.getElementById native code of Java but how to acheive it for Xrm

var ctrl = document.getElementById("letterlabel_c");
document.getElementById("letterlabel_c").style.width = "40%";


var ctrl = document.getElementById("letterlabel_d");
document.getElementById("letterlabel_d").style.display='none';

Sanjay