Rendered on a Line

All nodes that generate an inline box that are part of a line box are considered rendered on a line. These are line rendering nodes.

Any flat tree descendants of line rendering nodes are also considered part of a line if one of its clientRects overlaps with the position of the line box, and if all the following is true for each ancestor in the flat tree up to the line rendering node:

• the ancestor is an inline box; and
• the ancestor is not floating; and
• the ancestor does not have an absolute or fixed position.