Leaving out CSS-transitions and CSS-animations, the cascade sorts declarations according to the following table, !important user agent declarations have the highest priority, and normal user agent declarations have the lowest priority (see here):

Style Sheet Levels and Specificity

! important User Agent					.class	>	h2	>
! important User			#id	>	.class	>	h2	>
! important Author	inline-style	>	#id	>	.class	>	h2	>
Author	inline-style	>	#id	>	.class	>	h2	>
User			#id	>	.class	>	h2	>
User Agent					.class	>	h2

style: a declaration in the style attribute of an element has the same weight as a declaration with an id-based selector that is specified at the end of the style sheet.

    <style type="text/css">

        #x97z { color: blue;
                background-color:red; }

    </style

    <p id=x97z style="color: white;background-color:black">hello</p>
                        

(UA)UA !AU(UA)

With[{one = "(UA)", two = "U", three = "A"},

    StringTemplate["`1``2``3`!`3``2``1`"][one, two, three]]

//"(UA)UA!AU(UA)"
                        

W3C Cascade (Definitive)

W3C Cascade

W3C Cascade (Original)

Style sheets priority order (Stack Overflow)