I'm encountering an issue where the HTML and body width are not 100% when the browser window is less than 400px wide. Strangely, everything works perfectly when the window is wider than 400px.
Attempts to fix this include setting the body and html properties to padding:0 and margin: 0, as well as using a CSS reset * and border-box properties, but none of these solutions have resolved the problem for me.
To see the issue in action::
The orange background and content should fill the entire page, just like it does when the browser window is over 400px wide.