[css-color-4] Editorial cleanup of intro subsections.

Author: tabatkins

css-color-4/Overview.bs

@@ -131,20 +131,22 @@ Representing Colors: the <<color>> type</h2>
 	i.e. <nobr>''rgb(0 0 0 / 0%)''</nobr>.
 
 <h3 id="notes">
-Notes On Using Colors</h3>
+Accessibility and Conveying Information By Color</h3>
 
-	Although colors can add significant amounts of information to
-	documents and make them more readable, color by itself should not be the sole
-	means to convey important information. Please consider the
-	W3C Web Content Accessibility Guidelines [[WCAG20]] when including color in your documents.
+	Although colors can add significant information to documents
+	and make them more readable,
+	color by itself should not be the sole means to convey important information.
+	Authors should consider the W3C Web Content Accessibility Guidelines [[WCAG20]]
+	when using color in their documents.
 
-	<ul>
-		<li><a href="https://www.w3.org/TR/2008/REC-WCAG20-20081211/#visual-audio-contrast-without-color"><em>1.4.1 Use of Color:</em> Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element</a>
-	</ul>
+	> <a href="https://www.w3.org/TR/2008/REC-WCAG20-20081211/#visual-audio-contrast-without-color"><em>1.4.1 Use of Color:</em>
+	> Color is not used as the only visual means of conveying information,
+	> indicating an action, prompting a response, or distinguishing a visual element</a>
 
-<h3 id='sRGB'>Colors in sRGB</h3>
+<h3 id='sRGB'>
+Color Spaces of Untagged Colors</h3>
 
-	Colors specified in CSS, HTML, and untagged images are in the sRGB color space ([[!SRGB]])
+	Colors specified in HTML and [=untagged images=] are in the sRGB color space ([[!SRGB]])
 	unless otherwise specified.
 
 	An <dfn export>untagged image</dfn> is an image that is not explicitly assigned a color profile, as defined by the image format.
@@ -154,10 +156,10 @@ Notes On Using Colors</h3>
 	* At 720p, it is SMPTE ST 296 (same colorimetry as 709) [[!SMPTE296]]
 	* At 1080p, it is Recommendation ITU-R BT.709 [[!ITU-R-BT.709]]
 
-	Issue(287):
+	Issue(287): What is the colorspace for <{video}>?
 
-<h2 id='resolving-color-values'>
-Resolving Color values</h2>
+<h3 id='resolving-color-values'>
+Resolving <<color>> Values</h3>
 
 	Unless otherwise specified for a particular property,
 	[=specified value|specified=] colors are resolved to