How to style your Drupal 7 Navigation Menu

Iris.i

Very often we are restricted to having the drupal main menu navigation blog rendered through blocks on the page. What if you have a need to add the main menu directly to your template and target it for CSS with specific classes or id's?
Ideally this should be very simple to do but with the lack of documentation, drupal newbies seem to always find themselves tearing out their hair over seemingly 'simple' tasks like this.

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