diff --git a/book/figures/vars.tex b/book/figures/vars.tex
index 2eaa770..b082ac0 100644
--- a/book/figures/vars.tex
+++ b/book/figures/vars.tex
@@ -2,8 +2,9 @@
 \usepackage{tikz}
 
 \definecolor{codeblue}{RGB}{69, 161, 248}
+\definecolor{codegray}{RGB}{40, 40, 40}
 \usetikzlibrary{shapes,arrows}
-\tikzstyle{decision} = [diamond, draw, fill=codeblue, text=white,
+\tikzstyle{decision} = [diamond, draw, fill=codegray, text=white,
     text width=4.5em, text badly centered, node distance=3cm, inner sep=0pt]
 \tikzstyle{block} = [rectangle, draw, fill=codeblue,  text=white,
     text width=5em, text centered, rounded corners, minimum height=4em]