The Window.getComputedStyle() method returns a live read-only CSSStyleProperties object containing the resolved values of all CSS properties of an element, after applying active stylesheets and resolving any computation those values may contain.
Window.getComputedStyle()
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The
Window.getComputedStyle()method returns a live read-only CSSStyleProperties object containing the resolved values of all CSS properties of an element, after applying active stylesheets and resolving any computation those values may contain.MDN Reference