With the massive adoption of mobile devices with different formfactors, UI designers face the challenge of designing responsive UIs which are visually appealing across a wide range of devices. Designing responsive UIs requires a deep knowledge of HTML/CSS as well as responsive patterns - juggling through various design configurations and re-designing for multiple devices is laborious and time-consuming. We present DECOR, a recommendation tool for creating multi-device responsive UIs. Given an initial UI design, user-specified design constraints and a list of devices, DECOR provides ranked, device-specific recommendations to the designer for approval. Design space exploration involves a combinatorial explosion: We formulate it as a design repair problem and devise several design space pruning techniques to enable efficient repair. An evaluation over real-life designs shows that DECOR is able to compute the desired recommendations, involving a variety of responsive design patterns, in less than a minute.