In this article, the author introduces a mutative design system called Toucaan CSS, which optimizes web applications for various devices, starting with the Apple Watch. The Toucaan Switch Media Query (TSMQ) is a key feature, enabling CSS to be organized based on device orientation and screen size, allowing for more efficient and context-relevant design. The approach emphasizes extreme minimalism, especially for the small screens of devices like the Apple Watch, recommending the use of system fonts and avoiding excessive use of JavaScript, service workers, and inline video playback. The strategy involves creating device-specific stylesheets, such as watch.css, to enhance user experience by tailoring designs to the unique characteristics of each device, particularly focusing on the specific needs of the Apple Watch. The article also touches on the future-proof nature of TSMQ, suggesting that it can adapt to potential changes in device display modes and form factors.