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+# HCM Settings
+
+Several Firefox settings work together to determine how web content and browser chrome are rendered. They can be hard to keep track of! Use the flowcharts below for quick reference.
+
+## Settings that control color usage in browser chrome
+- OS HCM:
+	- Windows: High Contrast Mode in OS accessibility settings
+	- macOS: Increase Contrast in OS accessibility settings
+	- Linux: High Contrast Theme in OS accessibility settings
+- FF Theme (AKA FF Colorway)
+Note: OS HCM settings will only trigger HCM color usage in chrome if a user's FF theme is set to "system auto". If they have a pre-selected colorway or other FF theme (including explicit "Dark" or "Light") they will not see color changes upon enabling OS HCM.
+
+```{mermaid}
+flowchart TD
+A[Is OS HCM enabeld?]
+A -->|Yes| B[Is FF's theme set to System Auto?]
+B --> |Yes| C[Use OS HCM colors to render browser chrome]
+B -->|No| D[Use FF theme colors to render browser chrome]
+A -->|No| D
+```
+
+## Settings that control color usage in content
+- Colors Dialog (about:preferences > Manage Colors)
+	- Dropdown with options: Always, Only with High Contrast Themes, and Never
+	- Use System Colors checkbox
+	- Text, Background, Visited and Unvisited Link color inputs
+- Extensions like Dark Reader, or changes to user.css, may override author specified colors independent of HCM.
+
+```{mermaid}
+flowchart TD
+A[What is the value of the dropdown in the colors dialog?]
+A -->|Always|C
+
+A -->|Only with High Contrast Themes| B[Is a OS HCM enabled?]
+B -->|Yes| C[Is the Use System Colors checkbox checked?]
+C -->|Yes, and OS HCM is on| D[Use OS HCM colors to render web content]
+C -->|Yes, and OS HCM is off| D2[Use OS dark/light colors to render web content]
+C-->|No| E[Use colors dialog colors to render web content]
+
+B -->|No| F[Is a color-modifying web extension or color-modifying user.css change active?]
+F -->|Yes| G[Use web extension/user.css provided colors to render web content]
+F -->|No| H[Use author-provided colors to render web content]
+
+A -->|Never|F
+```