diff --git a/book/quarto/config/shared/base/diagram.yml b/book/quarto/config/shared/base/diagram.yml
index d15b35962..ca544dfa0 100644
--- a/book/quarto/config/shared/base/diagram.yml
+++ b/book/quarto/config/shared/base/diagram.yml
@@ -86,3 +86,5 @@ diagram:
         - '\definecolor{Thistle}{RGB}{222,132,191}'
         - '\definecolor{Siva}{RGB}{161,152,130}'
         - '\definecolor{crimson}{HTML}{A51C30}'
+        - '\definecolor{ethzblue}{HTML}{1F407A}'
+        - '\definecolor{accentcolor}{HTML}{1F407A}'
diff --git a/book/quarto/contents/vol2/introduction/introduction.qmd b/book/quarto/contents/vol2/introduction/introduction.qmd
index 18b6fe372..da3afdb86 100644
--- a/book/quarto/contents/vol2/introduction/introduction.qmd
+++ b/book/quarto/contents/vol2/introduction/introduction.qmd
@@ -1084,17 +1084,18 @@ To reason systematically about these interconnections, we need organizing framew
     label/.style={font=\scriptsize\itshape, text=black}
   }
 
-  % Nodes with standard colors — 4-Part Fleet Stack
-  \node[part, draw=RedLine, fill=RedL] (p4) at (0, 4.8) {Part IV: The Responsible Fleet\\ Security, Robustness, Sustainability, Governance};
-  \node[part, draw=GreenLine, fill=GreenL] (p3) at (0, 3.2) {Part III: Deployment at Scale\\ Inference, Performance, Edge, Operations};
-  \node[part, draw=BlueLine, fill=BlueL] (p2) at (0, 1.6) {Part II: Distributed ML\\ Training, Communication, Fault Tolerance, Orchestration};
-  \node[part, draw=BrownLine, fill=BrownL!40] (p1) at (0, 0) {Part I: The Fleet\\ Compute, Network, Data};
+  % Nodes with ETH Zurich Blue intensity gradient (like vol1 system stack with crimson)
+  % Bottom to top: 25% → 50% → 75% → 100% intensity
+  \node[part, draw=accentcolor!60, fill=accentcolor!25, text=accentcolor] (p1) at (0, 0) {Part I: The Fleet\\ Compute, Network, Data};
+  \node[part, draw=accentcolor!75, fill=accentcolor!50, text=accentcolor] (p2) at (0, 1.6) {Part II: Distributed ML\\ Training, Communication, Fault Tolerance, Orchestration};
+  \node[part, draw=accentcolor!90, fill=accentcolor!75, text=white] (p3) at (0, 3.2) {Part III: Deployment at Scale\\ Inference, Performance, Edge, Operations};
+  \node[part, draw=accentcolor, fill=accentcolor, text=white] (p4) at (0, 4.8) {Part IV: The Responsible Fleet\\ Security, Robustness, Sustainability, Governance};
 
-  % Background arrows showing constraint flow
+  % Background arrows showing constraint flow (ETHZ intensity)
   \begin{scope}[on background layer]
-    \draw[arrow, BlueLine!40] (p1.north) -- (p2.south);
-    \draw[arrow, GreenLine!40] (p2.north) -- (p3.south);
-    \draw[arrow, RedLine!40] (p3.north) -- (p4.south);
+    \draw[arrow, accentcolor!40] (p1.north) -- (p2.south);
+    \draw[arrow, accentcolor!40] (p2.north) -- (p3.south);
+    \draw[arrow, accentcolor!40] (p3.north) -- (p4.south);
   \end{scope}
 
   % Annotations
@@ -1117,11 +1118,11 @@ This layered progression structures the textbook's four Parts, each correspondin
     arrow/.style={-latex, thick, black!60}
   }
 
-  % Nodes with standard colors — 4-Part Fleet Stack
-  \node[part, draw=BrownLine, fill=BrownL!40] (p1) at (0, 0) {Part I: The Fleet};
-  \node[part, draw=BlueLine, fill=BlueL, below=0.8cm of p1] (p2) {Part II: Distributed ML};
-  \node[part, draw=GreenLine, fill=GreenL, below=0.8cm of p2] (p3) {Part III: Deployment at Scale};
-  \node[part, draw=RedLine, fill=RedL, below=0.8cm of p3] (p4) {Part IV: The Responsible Fleet};
+  % Nodes with ETH Zurich Blue intensity gradient (like vol1 system stack)
+  \node[part, draw=accentcolor!60, fill=accentcolor!25, text=accentcolor] (p1) at (0, 0) {Part I: The Fleet};
+  \node[part, draw=accentcolor!75, fill=accentcolor!50, text=accentcolor, below=0.8cm of p1] (p2) {Part II: Distributed ML};
+  \node[part, draw=accentcolor!90, fill=accentcolor!75, text=white, below=0.8cm of p2] (p3) {Part III: Deployment at Scale};
+  \node[part, draw=accentcolor, fill=accentcolor, text=white, below=0.8cm of p3] (p4) {Part IV: The Responsible Fleet};
 
   % Arrows
   \draw[arrow] (p1) -- (p2);
diff --git a/book/quarto/tex/theme-colors-vol2.tex b/book/quarto/tex/theme-colors-vol2.tex
index b25d4573a..a6b9a7b0b 100644
--- a/book/quarto/tex/theme-colors-vol2.tex
+++ b/book/quarto/tex/theme-colors-vol2.tex
@@ -5,4 +5,5 @@
 % Include this file BEFORE header-includes.tex
 % =============================================================================
 
-\definecolor{accentcolor}{HTML}{1F407A}  % ETH Zurich Blue
+\definecolor{ethzblue}{HTML}{1F407A}     % ETH Zurich Blue (official brand)
+\definecolor{accentcolor}{HTML}{1F407A}  % Alias for consistency