Many headaches can be caused by the cascade when using stylesheets.
Today I think I finally committed the priority to memory.
Priority in CSS
Low - Imported Stylesheets (@import)
Medium - Linked Stylesheets (<link>)
Medium High - Style blocks (<style>)
High - Inline Styles (style="" attribute)
Of course, this can be a challenge when combining selectors in various ways while using multiple methods to apply styles.