Setting image with to 1.5em seems to be aimed specifically at
the cross-reference icons in the Guide and Reference, and the
width should not apply to just any image in a margin note.
original commit: 463b81780a6e870d1f201e1b2408424bb02bfe77
Using
#lang scribble/base
produces HTML output in the old style, while
#lang scribble/manual
uses the new style.
To get the new style without switching to `#lang scribble/manual`,
use `manual-doc-style`.
Related changes include the addition of `css-style-addition` and
`js-style-addition`.
original commit: b520b66c4e8e54909c7d7b1126044e984989e8ef
