Jquery change all borders on classes

Why is not $( "demo" ).css("border", "1px solid #FFF");working? Every other part of the function is working, but not that one. The class "demo" is a regular from "page1.html".

<script>
var button = 0;
var activecolor = 0;
function pressbutton(a){
button = a;
var color1 = "#46B29D";
var color2 = "#F0CA4D";
var color3 = "#E37B40";
if (button === 1) {
activecolor = color1;
document.getElementById("button1").className = "activemenubutton";
document.getElementById("button2").className = "menubutton";
document.getElementById("button3").className = "menubutton";
} else if (button === 2){
activecolor = color2;
document.getElementById("button1").className = "menubutton";
document.getElementById("button2").className = "activemenubutton";
document.getElementById("button3").className = "menubutton";
} else if (button === 3){
activecolor = color3;
document.getElementById("button1").className = "menubutton";
document.getElementById("button2").className = "menubutton";
document.getElementById("button3").className = "activemenubutton";
}

document.getElementById("textholder").style.borderTop = "1px solid " + activecolor;
document.getElementById("textholder").style.borderBottom = "1px solid " + activecolor;
document.getElementById("textholder").style.color= activecolor;


$("#textholder").load("Page" + a + ".html");
$( "demo" ).css("border", "1px solid #FFF");

} //end of function

</script>