It's time to try to distinguish the common parts of the website. We will divide them into elements and attributes.
Elements are those parts of a site that exist independently. I mean that you could replace them and those changes would not affect the rest of the site. An example of an element is a footer or a menu. You could change the look of the footer (color, font, or border) but it wouldn't affect the menu or any other element.
An attribute is something that affects the whole site (all elements). An example of an attribute is page width. If you decide to make your website wider or narrower, you will probably have to redesign all of the elements to fit into the new space. Think of the footer mentioned previously. The footer is usually as wide as the whole page. If you make the site wider, you have to make the footer wider too.