1. A computer-implemented method, comprising: receiving, by a computer system, a request for a login web page of a web site, the request received from a computing device associated with a user account, the login web page configured to facilitate an authentication of the user account based at least in part on a username and a password; inserting, by the computer system in the login web page, a universal resource locator (URL) of a second web page of the web site and code, the code configured to, upon execution at the computing device: determine whether the URL and a cascading style sheets (CSS) attribute of the URL are present in a browser history stored at the computing device, and determine, based at least in part on presence of the URL and the CSS attribute in the browser history, that the second web page was accessed by the computing device prior to receiving the request for the login web page, the second web page accessed by the computing device prior to receiving the request based at least in part on a prior authentication of the user account via the login web page; providing, by the computer system to the computing device and based at least in part on the request, the login web page comprising the URL of the second web page and the code; receiving, by the computer system from the computing device, an indication that the second web page was accessed prior to receiving the request for the login web page, the indication received based at least in part on a determination by the code of the presence of the URL and the CSS attribute in the browser history upon an execution of the code at the computing device; and authenticating, by the computer system, the user account based at least in part on the indication.