This text examines how CSS containing blocks function and how the Blink rendering engine implements these rules within Chromium. It explains that a containing block is the essential rectangular reference used to determine the size and position of elements, with specific rules for static, absolute, and fixed positioning. Beyond traditional positioning, modern CSS properties like transforms, filters, and containment also establish new containing blocks that alter standard layout behavior. The source details Blink's internal architecture, describing how C++ classes like LayoutObject and ComputedStyle manage these relationships through efficient caching and mapping. By using a two-pass layout system, the engine ensures that out-of-flow elements are accurately positioned relative to their containers while optimizing performance. Ultimately, the document bridges the gap between abstract web standards and the technical execution required to render complex layouts.