Style sheets let you place things exactly where you want them to be on the page, using the distance in pixels from the top and the left of the browser window.

If you created a style for a heading tag,

. you set the color of your H3 tags to red.if you have 10 H3 tags on the page, and decide you would rather have your headings in blue, All you have to do is change the style of your H3 tag from the color red to blue. Changing the style once will adjust all of your H3 tags and they will now be all blue instead of red.

In CSS we keep design and content seperate.