I'm working from the code given here. I've got this:
\newcommand\Textbox[2]{%
\parbox[c][\dimexpr#1-7.7pt][c]{2cm}{\centering#2}}
\tikzstyle{partition}=[draw,
align=center,
color=blue,
rectangle split,]
\begin{tikzpicture}[font=\footnotesize]
\node[partition,
rectangle split parts=7,
rectangle split part fill={gray!30, blue!15}] (start) {
\textbf{Start}
\nodepart{two} \Textbox{30.0pt}{300 KB}
\nodepart{three}\Textbox{60.0pt}{600 KB}
\nodepart{four} \Textbox{35.0pt}{350 KB}
\nodepart{five} \Textbox{20.0pt}{200 KB}
\nodepart{six} \Textbox{75.0pt}{750 KB}
\nodepart{seven}\Textbox{12.5pt}{125 KB}
};
% 115 KB
\node[right=0.5em of start,
partition,
rectangle split parts=8,
rectangle split part fill={
gray!30,
blue!15, blue!15, blue!15, blue!15, blue!15, green!15, blue!15
}] (step1) {
\textbf{Step 1}
\nodepart{two} \Textbox{30.0pt}{300 KB}
\nodepart{three}\Textbox{60.0pt}{600 KB}
\nodepart{four} \Textbox{35.0pt}{350 KB}
\nodepart{five} \Textbox{20.0pt}{200 KB}
\nodepart{six} \Textbox{75.0pt}{750 KB}
\nodepart{seven}\Textbox{11.5pt}{115 KB}
\nodepart{eight}\Textbox{01.0pt}{10 KB}
};
% 500 KB
\node[right=0.5em of step1,
partition,
rectangle split parts=9,
rectangle split part fill={
gray!30,
blue!15, green!15, blue!15,blue!15,blue!15,blue!15, green!15, blue!15
}] (step2) {
\textbf{Step 2}
\nodepart{two} \Textbox{30.0pt}{300 KB}
\nodepart{three}\Textbox{50.0pt}{500 KB}
\nodepart{four} \Textbox{10.0pt}{100 KB}
\nodepart{five} \Textbox{35.0pt}{350 KB}
\nodepart{six} \Textbox{20.0pt}{200 KB}
\nodepart{seven}\Textbox{75.0pt}{750 KB}
\nodepart{eight}\Textbox{11.5pt}{115 KB}
\nodepart{nine} \Textbox{01.0pt}{10 KB}
};
% 358 KB
\node[right=0.5em of step2,
partition,
rectangle split parts=10,
rectangle split part fill={
gray!30,
blue!15, green!15, blue!15, blue!15, blue!15, green!15, blue!15, green!15, blue!15
}] (step3) {
\textbf{Step 3}
\nodepart{two} \Textbox{30.0pt}{300 KB}
\nodepart{three}\Textbox{50.0pt}{500 KB}
\nodepart{four} \Textbox{10.0pt}{100 KB}
\nodepart{five} \Textbox{35.0pt}{350 KB}
\nodepart{six} \Textbox{20.0pt}{200 KB}
\nodepart{seven}\Textbox{35.8pt}{358 KB}
\nodepart{eight}\Textbox{39.2pt}{392 KB}
\nodepart{nine} \Textbox{11.5pt}{115 KB}
\nodepart{ten} \Textbox{01.0pt}{10 KB}
};
% 200 KB
\node[right=0.5em of step3,
partition,
rectangle split parts=10,
rectangle split part fill={
gray!30,
blue!15, green!15, blue!15, blue!15, green!15, green!15, blue!15, green!15, blue!15
}] (step4) {
\textbf{Step 4}
\nodepart{two} \Textbox{30.0pt}{300 KB}
\nodepart{three}\Textbox{50.0pt}{500 KB}
\nodepart{four} \Textbox{10.0pt}{100 KB}
\nodepart{five} \Textbox{35.0pt}{350 KB}
\nodepart{six} \Textbox{20.0pt}{200 KB}
\nodepart{seven}\Textbox{35.8pt}{358 KB}
\nodepart{eight}\Textbox{39.2pt}{392 KB}
\nodepart{nine} \Textbox{11.5pt}{115 KB}
\nodepart{ten} \Textbox{01.0pt}{10 KB}
};
% 375 KB
\node[right=0.5em of step4,
partition,
rectangle split parts=11,
rectangle split part fill={
gray!30,
blue!15, green!15, blue!15, blue!15, green!15, green!15, green!15, blue!15, green!15, blue!15
}] (step5) {
\textbf{Step 5}
\nodepart{two} \Textbox{30.0pt}{300 KB}
\nodepart{three} \Textbox{50.0pt}{500 KB}
\nodepart{four} \Textbox{10.0pt}{100 KB}
\nodepart{five} \Textbox{35.0pt}{350 KB}
\nodepart{six} \Textbox{20.0pt}{200 KB}
\nodepart{seven} \Textbox{35.8pt}{358 KB}
\nodepart{eight} \Textbox{37.5pt}{375 KB}
\nodepart{nine} \Textbox{1.7pt}{17 KB}
\nodepart{ten} \Textbox{11.5pt}{115 KB}
\nodepart{eleven}\Textbox{01.0pt}{10 KB}
};
\end{tikzpicture}
What can I do to clean it up so that it works for the very smallest slices?