function visible(id){
	hidden()
	document.getElementById(id).className = "visible";
}

function hidden(){
	document.getElementById("cust").className = "hidden";
	document.getElementById("inter").className = "hidden";
	document.getElementById("tech").className = "hidden";
	document.getElementById("spec").className = "hidden";
} 

function trim(str, chars) {
    return ltrim(rtrim(str, chars), chars);
}

function ltrim(str, chars) {
    chars = chars || "\\s";
    return str.replace(new RegExp("^[" + chars + "]+", "g"), "");
}

function rtrim(str, chars) {
    chars = chars || "\\s";
    return str.replace(new RegExp("[" + chars + "]+$", "g"), "");
}