space below. The extra column contains more helpful tools: Layout contains information about the box model properties of the element. Note that flex and grid do not work yet. Computed, which contains all the 2.8 of the event-loop-processing-model In two places(one, two) in a window event-loop(the ScriptThread ), again as part of step 2.8 of the event-loop-processing-model. This needs to consolidated into one a subtle interaction between Servo's integration with SpiderMonkey's garbage collector and Rust's model for shared ownership. Since DOM objects in Servo are not uniquely owned, we must use RefCell / DomRefCell