Website not centering in computer screen

Question

Hello,
I'm building a website in dreamweaver and using fluid grid.
When the site is viewed on a screen larger than 1132px max-width, the site is rendering on the left side of the screen:
http://ourhtn.com/
I've place the header and footer outside the grid container and feel that this or other container element is causing the problem.
I can't figure out the solution; any help would be greatly appreciated.
Thanks so much,
Claude

Answer 1

Thanks for your quick response.  I appreciate your help.
I'll dig into this and compare what I've done with your example.
But I am confused, because the grid container is defined in my style sheet:
@media only screen and (min-width: 50px) and (max-width: 480px)
.gridContainer {
margin-left: auto;
margin-right: auto;
width: 95.35%;
padding-left: 1.275%;
padding-right: 1.275%;
clear: none;
float: none;
@media only screen and (min-width: 481px) and (max-width: 768px){
.gridContainer {
  width: 95.675%;
  padding-left: 1.1625%;
  padding-right: 1.1625%;
  clear: none;
  float: none;
  margin-left: auto;
  margin-right: auto;
@media only  screen
and (min-width: 769px) and (max-width: 959px)
.gridContainer {
width: 92.5%;
padding-left: 2.75%;
padding-right: 2.75%;
clear: none;
float: none;
margin-left: auto;
margin-right:auto;
@media
only screen and (min-width: 960px)
,gridContainer {
width: 90.5%;
padding-left: 3.75%;
padding-right: 3.75%;
clear: none;
float: none;
margin-left: auto;
margin-right: auto;
I am working on a template.  The only content I've placed in the grid container is a placeholder section tag #mainContent.
I placed header nav and footer outside of the grid.  Incorrect?