Reducing the gap around the frames of longtable

Question

When creating a long table, The following conflict occured in line of tables.

I need to fix it and make it a complete frame around the table.

I used the following codes in order to make a longtable.

\documentclass[a4paper,onesided,12pt]{report}


\usepackage[utf8x]{inputenc} % To use Unicode (e.g. Turkish) characters    
\renewcommand{\labelenumi}{(\roman{enumi})}    
\usepackage{amsmath, amsthm, amssymb}    
 % Some extra symbols    
\usepackage[bottom]{footmisc}    
\usepackage{cite}    
\usepackage{graphicx}    
\usepackage{longtable}    
\usepackage{multirow}    
\usepackage{subfigure}    
\usepackage{algorithm}    
\usepackage{algorithmic}    
\newlength{\mycolumnwidth}    
\setlength{\mycolumnwidth}{\textwidth-9cm-4\tabcolsep}

\begin{document}

\begin{longtable}{|m{9cm}|m{\mycolumnwidth}|}    
\caption{Tarık's emergent codes and corresponding themes}\\    
\toprule    
 RELEVANT CODES &   THEME \\    
 \toprule
 \endfirsthead 

\caption{Tarık's emergent codes and corresponding themes (continued)}\\    
\toprule
RELEVANT CODES &   THEME \\ 
\hline     
\endhead    

Graph representation & \multirow{1}{*}{Interpretation of graph} \\     
Graph completion & \\ 
\midrule    
Thinking about quadratic functions & \\     
Thinking about quadratic functions in real life 
& \multirow{1}{*}{Interpretation of function} \\     
Thinking about quadratic functions in physics & \\    
\midrule    
Finding a satisfactory answer to what question requires 
&\multirow{1}{*}{Make sense of model repr.}  \\ 
\midrule    
\pagebreak   
Looking interaction between his drawn model and given graph 
&\multirow{1}{*}{Alignment of model-graph} \\ 
Finding conflict when matching his graph and his  model & \\  
\bottomrule

\end{longtable}

\end{document}

Answer 1

Booktabs adds some padding around its rules, which is the cause of the non-intersecting horizontal and vertical lines. If you want them to intersect, and nevertheless have rules with varying thickness, you can either use another package such as boldline or makecell, or you deactivate the padding of rules in booktabs, and partly replacing it with an \extrarowheight.

I propose a code with the latter solution. In addition, I changed the code to have a single row between two horizontal rules, which is easy since the cells are in paragraph mode and results in a normal line spacing.

\documentclass[a4paper,onesided,12pt]{report}

%\usepackage{styles/fbe_tez}
\usepackage[utf8]{inputenc} % To use Unicode (e.g. Turkish) characters
\renewcommand{\labelenumi}{(\roman{enumi})}
\usepackage{amsmath, amsthm, amssymb}
 % Some extra symbols
\usepackage[bottom]{footmisc}
%\usepackage{cite}
\usepackage{graphicx}
\usepackage{ragged2e} 
\usepackage{array, booktabs, longtable, multirow}
\usepackage{subfigure}
\usepackage{algorithm, algorithmic}
\newlength{\mycolumnwidth}
\setlength{\mycolumnwidth}{\dimexpr\textwidth-9cm-4\tabcolsep}
\newcommand*{\nl}{\newline}

\begin{document}

\begingroup\setlength{\aboverulesep}{0pt}
\setlength{\belowrulesep}{0pt}
\setlength{\extrarowheight}{2pt}
\begin{longtable}{| m{9cm}| >{\arraybackslash\RaggedRight}m{\dimexpr\textwidth-9cm-4\tabcolsep}|}
\caption{Tarık's emergent codes and corresponding themes}\\
\toprule
 RELEVANT CODES & THEME \\
 \toprule
 \endfirsthead

\caption{Tarık's emergent codes and corresponding themes (continued)}\\
\toprule
RELEVANT CODES & THEME \\
\hline
\endhead

Graph representation \nl Graph completion & Interpretation of graph \\
\midrule 
Thinking about quadratic functions \nl
Thinking about quadratic functions in real life \nl
Thinking about quadratic functions in physics 
& Interpretation of function \\ 
\midrule
Finding a satisfactory answer to what question requires
& Make sense of model repr. \\
\midrule
\pagebreak
Looking interaction between his drawn model and given graph \nl
Finding conflict when matching his graph and his model 
& Alignment of model-graph \\ 
\bottomrule

\end{longtable}
\endgroup

\end{document}