 Container queries recently became stable across all modern browsers and allow for you to query a parent element's size and style values to determine the styles which should be applied to any of its children. Unlike media queries which can only access and leverage the information from the viewport and thus really only work on a page layout macro view, container queries are a more fine-tuned tool that support any number of style optimizations and layouts within layouts. In this inbox example, the primary inbox and favorite sidebar are both containers. The emails within them adjust their grid layout and show or hide the email timestamp based on available space. This is the exact same component within the page, just appearing in different views, and because we have a container query, their styles are dynamic. As we readjust the page size and the macro layout shifts, they look to their individually allocated space to make styling decisions. The sidebar becomes a top bar with more space and we see the internal layouts shift to adjust.