Specifically:

• Commit ac57d7c This adds a "width 50%" class which can be applied to blocks like [sidebar.width50]. I know that's mixing presentation with code to some degree, but a "half-width block" seems... often useful.

• Commit 36e9d38 This makes sidebar titles (which are optional) the same color, size, and font-weight as H2 titles, rather than being a lighter weight and weirdly brown. We might want to apply this to figure titles and others as well, but for now I want it for sidebars for sure.