Chromium’s Blink engine manages specific CSS overflow behaviors by distinguishing between scrollable containers and clipped elements. While standard combinations like visible and hidden are often reconciled into a single scrollable state, the introduction of the clip value allows for independent, single-axis masking. When developers pair horizontal visibility with vertical clipping, Blink generates an internal bitmask that defines a unique clipping region with infinite width but fixed height. This mechanism ensures that content spilling sideways remains viewable and interactive, whereas vertical overflow is strictly truncated without creating a scroll context. By separating these concerns, the engine prevents side effects like sticky positioning interference while maintaining precise control over painting and hit testing.