Merge pull request #151 from control-toolbox/ocots-patch-1

Update index.md

docs/src/index.md

@@ -15,7 +15,7 @@ P(<a href='https://control-toolbox.org/docs/ctproblems/stable/'>CTProblems</a>)
 P --> B
 F --> B
 D --> B
-style D fill:#FFF0F5
+style D fill:#FBF275
 ```
 
 !!! note "Install"