Browser window with 404 error message.

Web browser window with an error message is shown. the blue bar at the top has three small circles in red, yellow, and green. below the blue bar, the word "error" is prominently displayed in large red letters on a white background. underneath this, the number "404" appears in even larger red letters against a dark blue background. to the left of the "error" text, a yellow triangle contains a red exclamation mark.