[css-align-3] Fix the remaining changes that were accidentally reverted in e693915. Fixes #2934.

Author: tabatkins

css-align-3/Overview.bs

@@ -68,8 +68,6 @@ table.align-details { width: 100%; }
 <h2 id="intro">
 Introduction</h2>
 
-	<em>This section is not normative.</em>
-
 	CSS Levels 1 and 2 allowed for the alignment of text via 'text-align'
 	and the alignment of blocks by balancing ''margin/auto'' margins.
 	However, except in table cells,
@@ -86,6 +84,8 @@ Introduction</h2>
 	If implementors or anyone else notices a discrepancy,
 	please report this to the CSSWG as an error.
 
+	<em>This section (above) is not normative.</em>
+
 <h3 id="placement">
 Module interactions</h3>
 
@@ -236,7 +236,7 @@ Alignment Terminology</h2>
 			The <a>alignment container</a> is the rectangle that the <a>alignment subject</a> is aligned within.
 			This is defined by the layout mode,
 			but is usually the <a>alignment subject</a>’s containing block,
-			and assumes the writing mode of the box establishing the containing block.
+			and assumes the [=writing mode=] of the box establishing the containing block.
 
 		<dt><dfn export>fallback alignment</dfn>
 		<dd>
@@ -2105,7 +2105,7 @@ Determining the Baselines of a Box</h2>
 
 	For the purposes of finding the baselines of a box,
 	it and all its in-flow descendants with a scrolling mechanism (see the 'overflow' property)
-	must be considered as if scrolled to their origin.
+	must be considered as if scrolled to their initial scroll position.
 	Furthermore, if, in the case of a <a>scroll container</a> box,
 	the resulting position of a first (last) baseline
 	is past a box's end (start) border edge,