I have this array:

```
\documentclass[crop,tikz,convert={outext=.svg,command\unexpanded{pdf2svg \infile\space\outfile}},multi=false]{standalone}
\usepackage{xcolor}
\usepackage{tikz}
\usetikzlibrary{positioning, matrix, fit, arrows.meta, shapes.misc, backgrounds}

\definecolor{customBlue}{HTML}{0063A2}
\definecolor{customAzure}{HTML}{C4EDF9}
\definecolor{customGreen}{HTML}{009053}
\definecolor{customPurple}{HTML}{812C7C}
\definecolor{customBrown}{HTML}{943227}
\definecolor{customViolet}{HTML}{3F367B}
\definecolor{customPink}{HTML}{DA0F70}
\definecolor{bracket}{HTML}{00A3DA}

\begin{document}
  \begin{tikzpicture}[x=1cm,y=1.5cm,]
    \matrix (C) [
      matrix of nodes,
      nodes={draw, minimum size=6mm},
      inner sep=6pt, outer sep=0pt,
      column sep=-\pgflinewidth
    ] at (0, 3){
      $\textcolor{customBlue}{2}, sl^1_0, ic^1_0$ &
      $\textcolor{orange}{31}, sl^1_1, ic^1_1$ &
      $\textcolor{customBrown}{102}, sl^1_2, ic^1_2$ &
      $\textcolor{customPink}{187}, sl^1_3, ic^1_3 $
      \\
    };
    \node[above=3pt of C-1-1]{$levels[1]$};
    \node[below=3pt of C-1-1]{$0$};
    \scoped[on background layer] {
      \node[fill=customAzure, inner sep=0mm, fit=(C-1-2.north east)(C-1-2.south west) ] {};
    }
  \end{tikzpicture}
\end{document}

```

How can I draw a bracket between node `2` and node `102`? The result is something like:
[![enter image description here](https://i.stack.imgur.com/BdleR.png)](https://i.stack.imgur.com/BdleR.png)