XF 1.5 Where did I break something with the responsive design?

[Movie Prop Sites]

As I make my browser window smaller, the width of the Title and Description area of the forums on the home page decreases but the Latest Post information area does not decrease, nor does the side bar drop away. Eventually it leaves me with a page that looks like the image below. I can see from this forum that the way is SHOULD work is that the sidebar drops away and then the Latest Post information. For the life of me, I can't tell what I have changed or modified that has stopped my forum from operating in this same fashion. Please help me figure out what I have done.

If you want to look at the forum directly, it is http://www.405th.com/forums

 

[Movie Prop Sites]

Any help on this would be greatly appreciated.

 

[thomas1]

For what it's worth, it works perfectly on my iPhone.

 

[Movie Prop Sites]

For what it's worth, it works perfectly on my iPhone.

Mine as well. I am struggling with it mightily. I THINK I might have figured it out but it makes no sense to me.

The Default setting for the Right and Left Margin within the style property General>Page Width Controller is set to 1%. I had set both left and right to 10% and that seems to cause the problem. Actually, anything other than 1% seems to cause the problem. I don't know why that interacts with the responsive design but it seems to play hell with it, unless I am just misunderstanding something.