clean up video-dynamic-range

Author: vi-dot-cpp

mediaqueries-4/Overview.bs

@@ -1706,8 +1706,8 @@ Dynamic Range: the 'dynamic-range' feature</h3>
 	</pre>
 </h3>
 
-'@media/dynamic-range' represents the combination of brightness and color
-depth.
+'@media/dynamic-range' represents the combination of max brightness,
+color depth, and contrast ratio that are supported by the UA and output device.
 
 <dl dfn-type=value dfn-for="@media/dynamic-range">
 	<dt><dfn>high</dfn>
@@ -1733,19 +1733,18 @@ max brightness or low brightness as it relates to displays. As such, the
 determination for '@media/dynamic-range' and '@media/video-dynamic-range' will
 be defined by the user agent.
 
-<h3 id="video-prefixed-properties">
-Video Prefixed Properties scenarios</h3>
+<h3 id="video-prefixed-properties">Video Prefixed Feature</h3>
 
     Some user agents, including many TVs, render video and graphics in two
 	separate "planes" (bi-plane) with distinct screen characteristics. A set of
 	video-prefixed features is provided to describe the video plane.
 
-	Any bi-plane implementation **MUST** return values based on the video plane
+	Any bi-plane implementation must return values based on the video plane
 	for the following features: '@media/video-color-gamut'; '@media/video-width';
 	'@media/video-height'; '@media/video-resolution'; '@media/video-dynamic-range'.
-	All other features **MUST** return values based on the graphics plane.
+	All other features must return values based on the graphics plane.
 
-    Non bi-plane implementations **MUST** return the same values for
+    Non bi-plane implementations must return the same values for
 	video-prefixed features and their non-prefixed counterparts.
 
 <h3 id="video-color-gamut">
@@ -1778,23 +1777,11 @@ Video Dynamic Range: the 'video-dynamic-range' feature</h3>
 	</pre>
 </h3>
 
-'@media/video-dynamic-range' has the same values and definitions as '@media/dynamic-range',
-but describes the UA's and device's video plane.
+'@media/video-dynamic-range' represents the combination of max brightness,
+color depth, and contrast ratio that are supported by the UA and output device's
+video plane.
 
-<dl dfn-type=value dfn-for="video-dynamic-range">
-	<dt><dfn>high</dfn>
-	<dd>
-		If the following are true for the UA and the output device's video plane:
-		* color gamut is ''p3'' or ''rec2020''
-		* color depth is greater than 24 bit
-		* has a high contrast ratio
-	<dt><dfn>standard</dfn>
-	<dd>
-		If the following are true for the UA and the output device's video plane:
-		* color gamut is sRGB
-		* color depth is 24 bit or 8 bit per color component of RGB
-		* has a low contrast ratio
-</dl>
+Supported values are the same as dynamic-range.
 
 <h3 id="video-width">
 Video-Width: the '@media/video-width' feature</h3>