Assume there is only one $($:$p$:$)$ tag in the html file, the color of $($:$p$:$)$ tag is specified as green in the external style sheet $($mystyle$.$css$),$ red in the header's style section, and blue in the style attribute of the $($:$p$:$)$ tag, the paragraph will be displayed as:

green

red

blue

mix of $3$ colors