[css-color] more tidying

Author: svgeesus

css-color/Overview.bs

@@ -1607,21 +1607,18 @@ Converting LCH colors to Lab  colors</h3>
 <h2 id='grays'>
 Specifying Grays: the ''gray()'' functional notation</h2>
 
-<p class="issue">As suggested at San Francisco, keep the syntax here but make
-	gray(number, alpha?) an alias to Lab with a=b=0. However, this should be 
-	</p>
+<!-- As decided at San Francisco, this syntax is an alias to Lab with a=b=0.  -->
 
 	Grays are fully desaturated colors. The ''gray()'' functional notation simplifies 
 	specifying this common set of colors, so that only a single numerical parameter 
 	is required, and so that gray(50%) is a visual mid-gray (perceptually equidistant 
 	between black and white).
 
-
 	<pre class='prod'>
 	<dfn>gray()</dfn> = gray( <<number>>  [, <<alpha-value>>]? )
 	</pre>
 
-	The first argument specifies the shade of gray,
+	The first argument specifies the shade of gray, equal to the CIE Lightness,
 	while the second optional argument specifies the alpha channel of the gray.
 
 <h3 id='gray-to-rgb'>
@@ -1631,8 +1628,9 @@ Converting gray colors to sRGB  colors</h3>
 but the last step are linear calculations and can be combined.</p>
 
 <ol>
-	<li>Convert to D65-adapted Lab by setting L to the gray value, a and b to 0
-	<li>Convert Lab to (D65-adapted) XYZ (<em>No</em> Bradford transform)
+	<li>Convert to Lab by setting L to the gray value, a and b to 0
+	<li>Convert Lab to XYZ 
+	<li> Adapt from D50 to D65 (Bradford transform)
 	<li>Convert from (D65-adapted) CIE XYZ to linear sRGB
 	<li>Convert from linear-light sRGB to sRGB (do gamma correction)
 </ol>
@@ -1692,13 +1690,14 @@ The color function takes an indentifier as the first parameter, followed by as m
 numerical parameters as are needed (three for an RGB colorspace, four for CMYK, 
 one for greyscale, and so on). An optional, comma-separated alpha value is also supported.
 The identifier is either one of the predefined spaces 
-(<i>p3</i> or <i>rec2020</i>) or the name of a profile.
+(<i>p3</i> or <i>rec2020</i>) or the name of a profile. An optional fallback may be specified
+(an sRGB color, or indeed another color() function).
 
 <pre class="issue">Decided at San Francisco to add a larger set of common predefined spaces 
 	like AdobeRGB, ProPhoto RGB, and so on. Also coated and uncoated swop, etc, etc. </pre>
 
 	<pre class='prod'>
-		<dfn>color()</dfn> = color( <<ident>> , <<number>>+ [, <<number>>])
+		<dfn>color()</dfn> = color( <<ident>> , <<number>>+ [, <<alpha-value>>]? [, <<fallback>>]?)
 	</pre>
 
 	<p class="issue">How to handle cases where there are too many, or too few, numbers supplied?
@@ -1746,10 +1745,11 @@ The ITU Rec.2020 [[!Rec.2020]]
 Rec.2020 transfer function has the same form as the one for sRGB, but with 
 the constants at higher precision to cope with 10 or 12-bit components:
 
-<pre> E < β ? 4.5 * E : α * Math.pow(E, 0.45) - (α - 1);
+<pre class="lang-javascript"> E < β ? 4.5 * E : α * Math.pow(E, 0.45) - (α - 1);
 </pre>	
 
-Where α=1.09929682680944  and β=0.018053968510807 . 
+Where α=1.09929682680944  and β=0.018053968510807 
+<!-- full-precision constants here, not the rounded ones for 10 or 12bit components -->. 
 
 <h4 id="predefined-to-lab">Converting predefined colorspaces to Lab</h4>
 
@@ -2475,7 +2475,7 @@ Guaranteeing Adequate Contrast: the ''contrast'' adjuster</h3>
 			<code>((channel + 0.055) / 1.055) ^ 2.4</code>.
 
 			Note: This reverses the logarithmic power scaling of the sRGB gamut,
-			so the value of the channel is approximately linear related to the amount of light required to represent it.
+			so the value of the channel is  linear with respect to the amount of light produced.
 
 		<li>
 			The luminance is: