After transitioning ASP.NET from VS2010 to VS2017, an issue emerged.
The problem manifests when loading the page in a browser - it briefly flickers, displaying the content as though the CSS is not applied before suddenly applying it.
Here's a screenshot of the page during loading: https://i.sstatic.net/qU9wp.png
And here's a screenshot after the page has fully loaded: https://i.sstatic.net/9xFqY.png