CSS Styles Not Displaying In Dreamweaver Design Mode

This is the problem I witnesed with a colleague at office and now today it happened with me. I opened a webpage in dreamweaver and the CSS styles were not showing up. All the webpage was naked and colorless in design mode. I wondered. I doubled checked the CSS styles in head section. the script was there.

Searching over google did not help me as there was other issues about CSS and not this one. Then I kept looking in software options and did some settings and I got my visuals back after some minutes.
Here are the steps to solve the problem.

In dreamweaver Go to View - Visual Aids

Following options must be checked
- CSS Layout Box Model
- CSS Layout Outlines

Moreover Go to View - Styles Rendering

Make sure that following option is checked
- Screen Media Type

Interesting fact is this; even these option were checked with me but still CSS Styles were not displaying.
I figured out that I was using CSS Styles Script in another page header.php and so it was outside the webpage which I was editing but header was included in that page.

Here I did something more…
I defined site. Go to Site - Manage Sites
Define the site there, give it a name, give path where the pages are located and configure other options.
When site was defined then dreamweaver got it that where are rest of the pages and CSS was back and my page was again colorful in design mode.
Try this.