Hi, Angela,
I would say, yes, to "...standard to load initial page data this way." But, NO, to CSS. This is styling the page. I agree it is a great spot to modify some login page code to your own purpose.
But, to say it is standard to load initial page ->data<- is true, with maybe an XHR get to populate some menus or something, but it absolutely is not standard to style your page at this juncture. CSS is used for that, and since DojoJS is being used throughout the project, that also has CSS control over its themes. But, it doesn't start ripping src tags from image nodes and assigning them to CSS style properties.
I'd say this was decidedly non-standard. Like the favicon.ico being in two places for the same app. I mean, the "Ask" (help pages) favicon could vary from the main app, but the login and main should be the same...
App:
./OAuthServer/wwwroot/images/favicon.ico
Login:
./Innovator/Client/images/favicon.ico
Ask:
./Innovator/Client/WebHelp/APIReferenceDotNet/Html/icons/favicon.ico
./Innovator/Client/WebHelp/APIReferenceJavaScript/Html/icons/favicon.ico
Anyway, I digress.
I'm just saying from a development aspect in customization of the "look" I'd expect the developer to be able to put styles in one CSS file and not worry about it... Never need to go, "Why does this thing keep writing over my style?"
Also, using LESS or SASS would be rad so you could just plug in some colors in one spot and have it trickle down.
That's my opinion.
Neil