[css-display-3] Add 'unless otherwise specified' to handle BODY propagation nonsense. #3260

Author: fantasai

css-display-3/Overview.bs

@@ -1033,7 +1033,9 @@ Appendix A: Glossary</h2>
 			however it is often derived from the dimensions of a box.
 			If properties of a containing block are referenced,
 			they reference the values on the box that generated the containing block.
-			(For the <a>initial containing block</a>, the values are taken from the root element.)
+			(For the <a>initial containing block</a>,
+			values are taken from the root element
+			unless otherwise specified.)
 			See [[CSS2]] <a href="https://www.w3.org/TR/CSS2/visuren.html#containing-block">Section 9.1.2</a>
 			and <a href="https://www.w3.org/TR/CSS2/visudet.html#containing-block-details">Section 10.1</a> for details.