Site is not responsive

I can't get my site at www.leevalleylions.co.uk to be responsive. I have the "Disable Responsive Design" box is unticked and the slider on my home page has been set up correctly, as far as I can see. I have the following among my custom CSS: /* For Screen above 1000px */ @media screen and (min-width: 1000px) { #header-menu ul.menu a { font-size: 14px; }} #page {width: 995px;} #secondary {width: 185px; border-right: 1px solid #e6e6e6; padding-right: 10px; height: 100%;} Is this what is stopping the page from scaling down? If so, how do I change it so that my site layout remains intact, please? It was about 4 years ago that I set up the design and from what I can remember I had problems with the layout collapsing when the widths for the sidebar/main section weren't specified). Many thanks.