docs: remove reference to system props

Author: rezrah

docs/content/philosophy.md

@@ -8,7 +8,7 @@ We are focusing primarily on presentational components that help standardize com
 
 ## Assume that people will break the rules, provide safe ways for them to do so
 
-While we aim to standardize design in Primer React, we also provide some flexibility with constraint-based props. We offer system props via [styled-system](https://github.com/styled-system/styled-system) to allow users of the components to make small customizations, such as color and spacing, using values from the theme. Users also have the option to override the theme with a theme of their own.
+While we aim to standardize design in Primer React, we also provide additional styling flexibility through the [`sx` prop](/overriding-styles). This enables small customizations to color and spacing, using values from the theme. Users also have the option to override the theme with a theme of their own.
 
 ## Pattern Components vs Helper Components
 

docs/content/theming.md

@@ -50,7 +50,7 @@ Some components may break if your custom theme does not include all the same key
 
 ## Referencing theme values
 
-You can reference theme values in your application using [system props](/system-props), the [`sx` prop](/overriding-styles), the `themeGet` function, or the `useTheme` hook.
+You can reference theme values in your application using the [`sx` prop](/overriding-styles), the `themeGet` function, or the `useTheme` hook.
 
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