EDIT: This bug is Webview overriding the default minimum font size. In my example, Webview sets the minimum font-size to 8px somewhere. The solution is below :
I found that setting the following webview settings will act as a workaround for this bug.
mWebView.getSettings().setMinimumFontSize(1);
mWebView.getSettings().setMinimumLogicalFontSize(1);
setMinimumFontSize
These settings really should only be honored for actual text display, not rem based positioning/sizing. This must but an android webview bug.