When a browser reads a style sheet, it will format the HTML document according to the information in the style sheet.

Three Ways to Insert CSS

All the styles in a page will "cascade" into a new "virtual" style sheet by the following rules, where number one has the highest priority:
  1. Inline style (inside an HTML element)
  2. External and internal style sheets (in the head section)
  3. Browser default
So, an inline style has the highest priority, and will override external and internal styles and browser defaults.