You will have to change the widths in the 'Actinic Stylesheet' (Design | Library | Layouts tab | Web Page Outer Layouts group) for the following styles:
.page_header_content (line 11)
.page_menu_content (line 73)
.page_body_content (line 101)
.page_body_content_right_column (line 111)
.page_footer_content (line 125)
Line numbers are as set in a default stylesheet. They may vary if you have edited it.
You may also want to change the product list width (Settings | Site Options | Layouts tab | Products group).
As an example, you could set the '.page_header_content', '.page_menu_content', '.page_body_content' and '.page_footer_content' styles to a width of 900px and the '.page_body_content_right_column' and 'product list width' to 700px but you may have to play around with the widths until you get the desired effect.
.page_header_content (line 11)
.page_menu_content (line 73)
.page_body_content (line 101)
.page_body_content_right_column (line 111)
.page_footer_content (line 125)
Line numbers are as set in a default stylesheet. They may vary if you have edited it.
You may also want to change the product list width (Settings | Site Options | Layouts tab | Products group).
As an example, you could set the '.page_header_content', '.page_menu_content', '.page_body_content' and '.page_footer_content' styles to a width of 900px and the '.page_body_content_right_column' and 'product list width' to 700px but you may have to play around with the widths until you get the desired effect.