Why should you use CSS Style Sheets in all Website Development?

CSS (Cascading Style Sheets) Style Sheets are an easy way to control how your web pages look.  Basic CSS allows you to control fonts, text, colors, backgrounds and margins across all pages within your website. 

For Example, if your logo needs to be 5 pixels from the top and 10 pixels from the left on all of your pages,  it is very easy to define this positioning in your style sheet.