[css-color-5] add ids to h4s

Author: svgeesus

css-color-5/Overview.bs

@@ -235,7 +235,7 @@ The following sections outline the relative color syntax for each color function
 
 Issue: A future version of this specification may define a relative syntax for ''color()'' as well.
 
-<h4>Relative RGB colors</h4>
+<h4 id="relative-RGB">Relative RGB colors</h4>
 
 The grammar of the ''rgb()'' function is extended as follows:
 
@@ -252,7 +252,7 @@ When an origin color is present, the following keywords can also be used in this
 - 'b' is a <<percentage>> that corresponds to the origin color's blue channel after its conversion to sRGB
 - 'alpha' is a <<percentage>> that corresponds to the origin color's alpha transparency
 
-<h4>Relative HSL colors</h4>
+<h4 id="relative-HSL">Relative HSL colors</h4>
 
 The grammar of the ''hsl()'' function is extended as follows:
 
@@ -268,7 +268,7 @@ When an origin color is present, the following keywords can also be used in this
 - 'l' is a <<percentage>> that corresponds to the origin color's HSL lightness after its conversion to sRGB
 - 'alpha' is a <<percentage>> that corresponds to the origin color's alpha transparency
 
-<h4>Relative HWB colors</h4>
+<h4 id="relative-HWB">Relative HWB colors</h4>
 
 The grammar of the ''hwb()'' function is extended as follows:
 
@@ -283,7 +283,7 @@ When an origin color is present, the following keywords can also be used in this
 - 'b' is a <<percentage>> that corresponds to the origin color's HWB blackness after its conversion to sRGB
 - 'alpha' is a <<percentage>> that corresponds to the origin color's alpha transparency
 
-<h4>Relative Lab colors</h4>
+<h4 id="relative-Lab">Relative Lab colors</h4>
 
 The grammar of the ''lab()'' function is extended as follows:
 
@@ -320,7 +320,7 @@ When an origin color is present, the following keywords can also be used in this
 	</pre>
 </div>
 
-<h4>Relative LCH colors</h4>
+<h4 id="relative-LCH">Relative LCH colors</h4>
 
 The grammar of the ''lch()'' function is extended as follows: