[css-color-hdr][editorial] reword

Author: svgeesus

css-color-hdr-1/Overview.bs

@@ -210,7 +210,8 @@ It is affected by viewing flare
 and so the actual value depends on the viewing conditions.
 
 <dfn export>Linear dynamic range</dfn> is the [=luminance=] ratio
-between the <em>lightest</em> and the <em>darkest</em> colors.
+between the <em>lightest</em> and the <em>darkest</em> colors
+that can be displayed.
 
 <dfn export>Dynamic range</dfn> is the base-2 logarithm of [=linear dynamic range=],
 because our eyes percieve brightness on a logarithmic scale.