Help with divs moving when page is resized

Hey all. First of all I’d just like to say this was the most appropriate section of the forum I could find in order to post this. My apologies if it should have been posted elsewhere.

So, the problem is to do with resizing the browser window. I’d like the bottom scroll bar to appear when the page is resized horizontally, but instead my divs are sliding across the page. If it’s not completely clear what I’d like to achieve, an example can be seen when you resize this page.

Here is my current CSS:


@charset "utf-8";
/* CSS Document */

body {
	background-image: url(images/bg.gif);
	background-repeat: repeat;
	text-align: center;
}

@font-face {
	font-family: cambria;
	src: url('fonts/cambria.ttc');
}

#wrapper1 {
	width: 70%;
	margin: 0 auto;
	margin-top: 0;
	margin-bottom: 0;
	text-align: left;

}

#wrapper2 {
	width: 70%;
	margin: 0 auto;
	margin-top: 0;
	margin-bottom: 0;
	text-align: left;
	
}

#header {
	width: auto;
	height: auto;
}

#header #logo {
	float: left;
}

#header #googleads {
	float: right;
	margin-top: 35px;
}

#line {
	width: 100%;
	height: 4px;
	background-image:url(images/line.gif);
	background-repeat: repeat;
	float: left;
	margin-top: 10px;
}

#wrapper2 #intro {
	font-family: cambria, Arial;
	font-size: 48px;
	color: #ffffff;
	float: left;
	margin-top: 10px;
	text-shadow: 0px -1px 0px #4e4e4e;
}

#wrapper2 #intro span {
	color: #1d91d0;
}

#wrapper2 #rightcol {
	float: right;
	width: 33%;
	height: auto;
	margin-top: 10px;
	text-align: center;
}

#wrapper2 #rightcol span {
	margin: 0 7px 0 7px;
	font-family: cambria, Arial;
	font-size: 16pt;
	color: #202020;
}

#wrapper2 #rightcol .adboxl {
	float: left;
	width: 125px;
	height: 125px;
	background-color: #e4e4e4;
	border: 1px solid #8b9390;
}

#wrapper2 #rightcol .adboxr {
	float: right;
	width: 125px;
	height: 125px;
	background-color: #e4e4e4;
	border: 1px solid #8b9390;
}

I appreciate that my CSS coding is not too great, but I am hoping that my problem can be solved without any major changes to the current structure of my CSS.