Detail about <number>s in rgb-related color functions and glossary (m…

…dn#28962)

* color number detail

* color() args

* 16,777,216

* Update files/en-us/glossary/rgb/index.md

Co-authored-by: yarusome <97945148+yarusome@users.noreply.github.com>

* Update files/en-us/glossary/rgb/index.md

Co-authored-by: yarusome <97945148+yarusome@users.noreply.github.com>

* Update files/en-us/web/css/color_value/rgb/index.md

Co-authored-by: yarusome <97945148+yarusome@users.noreply.github.com>

* Note: sRGB/rounding

---------

Co-authored-by: Sideways S <sidewayss@users.noreply.github.com>
Co-authored-by: yarusome <97945148+yarusome@users.noreply.github.com>

files/en-us/glossary/rgb/index.md

@@ -10,11 +10,11 @@ _Red-Green-Blue_ (**RGB**) is a color model that represents colors as mixtures o
 
 Alone an RGB value has no meaning. A color model defines how the three components relate to a color space. Graphically, a point in a three-dimensional grid or cube represents a color. Each dimension (or axis) corresponds to a different channel. The RGB color model is then a _cubic_, or _Cartesian_, coordinate system of the underlying color space.
 
-For the web, the underlying color space for an RGB value is _sRGB_ (Standard RGB), and each RGB component is a number between 0 and 255. Float values are supported.
+For the web, the underlying color space for an RGB value is _sRGB_ (Standard RGB), and each RGB component is a number between 0 and 255.
 
 Note that there are other RGB color spaces, like the _Adobe RGB_ color space, that can represent a wider {{glossary("gamut")}} of color than the _sRGB_ color space. The coordinates in _sRGB_ and _Adobe RGB_ are different.
 
-There are many ways to describe the RGB components of a color. In {{Glossary("CSS")}} they can be represented as a single 24-bit integer in hexadecimal notation (for example, `#add8e6` is light blue), or in functional notation, [`rgb()`](/en-US/docs/Web/CSS/color_value/rgb) as three separate floats between 0 and 255 (for example, `rgb(46 139.5 87)`). In {{Glossary("OpenGL")}}, {{Glossary("WebGL")}}, and {{Glossary("GLSL")}} the red-green-blue components are fractions (floating-point numbers between 0.0 and 1.0), although in the actual color buffer they are typically stored as 8-bit integers.
+There are many ways to describe the RGB components of a color. In {{Glossary("CSS")}} they can be represented as a single 24-bit integer in hexadecimal notation (for example, `#add8e6` is light blue), or in functional notation, [`rgb()`](/en-US/docs/Web/CSS/color_value/rgb) as three separate numbers between 0 and 255 (for example, `rgb(46 139.5 87)`). There are also the `srgb`, `srgb-linear`, `a98-rgb`, and `prophoto-rgb` color spaces for the [`color()`](/en-US/docs/Web/CSS/color_value/color) function.
 
 RGB is not the only color model that can represent the _sRGB_ color space. Cylindrical coordinate systems like the [`HSL`](/en-US/docs/Web/CSS/color_value/hsl) (_hue-saturation-lightness_) or [`HWB`](/en-US/docs/Web/CSS/color_value/hwb) (_hue-whiteness-blackness_) color models are also used to represent a sRGB color on the web.
 

files/en-us/web/css/color_value/color/index.md

@@ -28,7 +28,7 @@ Functional notation: `color(colorspace c1 c2 c3[ / A])`
 
 - `c1`, `c2`, `c3`
 
-  - : {{CSSXref("number")}}, {{CSSXref("percentage")}} values or the keyword `none`, which provide the component values in the color space.
+  - : {{CSSXref("number")}} between 0 and 1, a {{CSSXref("percentage")}} or the keyword `none`, which provide the component values in the color space.
 
 - `A` {{optional_inline}}
 

files/en-us/web/css/color_value/hsl/index.md

@@ -37,6 +37,8 @@ Functional notation: `hsl(H S L[ / A])`
 - `A` {{optional_inline}}
   - : An {{CSSXref("<alpha-value>")}} or the keyword `none`, where the number `1` corresponds to `100%` (full opacity).
 
+> **Note:** This functional notation serializes to sRGB values, and the values of the red, green, blue components may be rounded in serialization.
+
 > **Note:** See [Missing color components](/en-US/docs/Web/CSS/color_value#missing_color_components) for the effect of `none`.
 
 ### Formal syntax

files/en-us/web/css/color_value/hwb/index.md

@@ -7,7 +7,7 @@ browser-compat: css.types.color.hwb
 
 {{CSSRef}}
 
-The **`hwb()`** functional notation expresses a given color according to its hue, whiteness, and blackness. An optional alpha component represents the color's transparency.
+The **`hwb()`** functional notation expresses an {{glossary("RGB", "sRGB")}} color according to its hue, whiteness, and blackness. An optional alpha component represents the color's transparency.
 
 {{EmbedInteractiveExample("pages/css/function-hwb.html")}}
 
@@ -36,6 +36,8 @@ Functional notation: `hwb(H W B[ / A])`
 
   - : An {{CSSXref("<alpha-value>")}} or the keyword `none`, where the number `1` corresponds to `100%` (full opacity).
 
+> **Note:** This functional notation serializes to sRGB values, and the values of the red, green, blue components may be rounded in serialization.
+
 > **Note:** See [Missing color components](/en-US/docs/Web/CSS/color_value#missing_color_components) for the effect of `none`.
 
 ### Formal syntax

files/en-us/web/css/color_value/rgb/index.md

@@ -31,6 +31,8 @@ Functional notation: `rgb(R G B[ / A])`
 - `A` {{optional_inline}}
   - : An {{CSSXref("<alpha-value>")}} or the keyword `none`, where the number `1` corresponds to `100%` (full opacity).
 
+> **Note:** This functional notation serializes to sRGB values, and the values of the red, green, blue components may be rounded in serialization.
+
 > **Note:** See [Missing color components](/en-US/docs/Web/CSS/color_value#missing_color_components) for the effect of `none`.
 
 ### Formal syntax