Improving site performance by shipping more CSS

GitHub engineers analyzed the CSS shipped by their site and found that a significant portion was not being used. They used a tool to minify and optimize the CSS, and then implemented a feature to automatically remove unused CSS from the build process. As a result, the site's CSS size was reduced by 1.1 MB, which improved page load times by 1.5 seconds on average for users with slow connections. The team also used a tool to visualize the CSS usage and found that 70% of the CSS was not being used.