Transferring web-application prerequisite files while authentication interface occludes web-application interface

A system including non-transitory media encoded with code that, when executed using hardware, causes the hardware to implement a process including:

• a web-application server responding to an access request from a web browser by transmitting to the web browser a parent document, the parent document identifying an authentication location, the access request being a request to use a web application executing on the web-application server, the web application having associated prerequisite files that are to be transferred to the web browser so that the user can use the web application;
• the web browser transmitting an authentication request to the authentication location;
• in response to the authentication request, an authentication program transmitting to the web browser a child document, the child document at least partially occluding the parent document, the child document presenting an authentication user interface;
• the authentication program making an authentication determination whether or not the user is authenticated based at least in part on the user's interaction with the authentication user interface;
• the web application, after a time the child document is transmitted and before a time the authentication determination is made, at least partially transferring the prerequisite files;
• and
• in the event the user is authenticated, causing the child document to be removed so that the parent document is no longer occluded by the child document so that the user can use the web application once the prerequisite files have been transferred.