diff --git a/notes/sections/6.md b/notes/sections/6.md
index de01c77..d124686 100644
--- a/notes/sections/6.md
+++ b/notes/sections/6.md
@@ -23,7 +23,6 @@ where:
 \hypertarget{fig:slit}{%
 \centering
 \begin{tikzpicture}
-  \definecolor{cyclamen}{RGB}{146, 24, 43}
   % Walls
   \draw [thick] (-1,3)  -- (1,3)  -- (1,0.3)  -- (1.2,0.3)  -- (1.2,3)
                        -- (9,3);
@@ -141,7 +140,6 @@ For a better understanding, see @fig:dot_conv.
 \hypertarget{fig:dot_conv}{%
 \centering
 \begin{tikzpicture}
-  \definecolor{cyclamen}{RGB}{146, 24, 43}
   % original histogram
   \draw [thick, cyclamen, fill=cyclamen!05!white] (0.0,0) rectangle (0.5,2.5);
   \draw [thick, cyclamen, fill=cyclamen!05!white] (0.5,0) rectangle (1.0,2.8);
@@ -277,7 +275,6 @@ Thus, only $n$ real numbers are required to store the half-complex sequence
 \hypertarget{fig:reorder}{%
 \centering
 \begin{tikzpicture}
-  \definecolor{cyclamen}{RGB}{146, 24, 43}
   % standard histogram
   \draw [thick, cyclamen] (0.5,0) -- (0.5,0.2);
   \draw [thick, cyclamen, fill=cyclamen!25!white] (1.0,0) rectangle (1.5,0.6);