favor module links over spec links (mdn#40783)

* favor module links over spec links

* uppercase

Author: estelle

files/en-us/web/css/css_values_and_units/css_data_types/index.md

@@ -45,7 +45,7 @@ These types include keywords and identifiers as well as strings, and URLs.
 
 ## Numeric data types
 
-These data types are used to indicate quantities, indexes, and positions. The majority of these are defined in the Values and Units specification, however additional types are described in other specifications where they are specific to that specification alone — for example the `fr` unit in [CSS grid layout](https://drafts.csswg.org/css-grid-1/#fr-unit).
+These data types are used to indicate quantities, indexes, and positions. The majority of these are defined in the CSS values and units module, however additional types are described in other modules where they are specific to that specification alone — for example the `fr` unit in the [CSS grid layout](/en-US/docs/Web/CSS/CSS_grid_layout) module.
 
 - {{cssxref("<integer>")}}
   - : One or more decimal units 0 through 9.
@@ -90,7 +90,7 @@ Some CSS properties can take a dimension or a percentage value. In this case the
 
 ## Color
 
-[The CSS Color Specification](https://drafts.csswg.org/css-color-4/) defines the {{cssxref("<color>")}} data type, and other types which relate to color in CSS.
+The [CSS color](/en-US/docs/Web/CSS/CSS_color) module defines the {{cssxref("<color>")}} data type, and other types which relate to color in CSS.
 
 - {{cssxref("<color>")}}
   - : Specified as a keyword or a numerical color value.
@@ -101,7 +101,7 @@ Some CSS properties can take a dimension or a percentage value. In this case the
 
 ## Images
 
-[The CSS Images Specification](https://drafts.csswg.org/css-images-3/) defines the data types which deal with images, including gradients.
+The [CSS images](/en-US/docs/Web/CSS/CSS_images) module defines the data types which deal with images, including gradients.
 
 - {{cssxref("<image>")}}
   - : A URL reference to an image or a color gradient.
@@ -144,4 +144,4 @@ These data types are used in [CSS math function](/en-US/docs/Web/CSS/CSS_Values_
 
 - [CSS values and units](/en-US/docs/Web/CSS/CSS_Values_and_Units) module
 - [Learn: Values and units](/en-US/docs/Learn_web_development/Core/Styling_basics/Values_and_units)
-- [CSS Functional Notation](/en-US/docs/Web/CSS/CSS_Values_and_Units/CSS_Value_Functions)
+- [CSS functional notation](/en-US/docs/Web/CSS/CSS_Values_and_Units/CSS_Value_Functions)