The length of the observed element's border box in the block dimension.
The length of the observed element's border box in the block dimension. For boxes with a horizontal writing-mode, this is the vertical dimension, or height; if the writing-mode is vertical, this is the horizontal dimension, or width.
The length of the observed element's border box in the inline dimension.
The length of the observed element's border box in the inline dimension. For boxes with a horizontal writing-mode, this is the horizontal dimension, or width; if the writing-mode is vertical, this is the vertical dimension, or height.