  Designing responsive visualizations can be cast as applying transformations
to a source view to render it suitable for a different screen size. However,
designing responsive visualizations is often tedious as authors must manually
apply and reason about candidate transformations. We present Cicero, a
declarative grammar for concisely specifying responsive visualization
transformations which paves the way for more intelligent responsive
visualization authoring tools. Cicero's flexible specifier syntax allows
authors to select visualization elements to transform, independent of the
source view's structure. Cicero encodes a concise set of actions to encode a
diverse set of transformations in both desktop-first and mobile-first design
processes. Authors can ultimately reuse design-agnostic transformations across
different visualizations. To demonstrate the utility of Cicero, we develop a
compiler to an extended version of Vega-Lite, and provide principles for our
compiler. We further discuss the incorporation of Cicero into responsive
visualization authoring tools, such as a design recommender.
