\chapter{Screenshots of my application}
\label{app:screen}

The screenshots.
\begin{figure}[ht]
    \centering
    \includegraphics[width=\textwidth]{3_back_matter/appendices/images/mockup.png}
    \caption{Mockup of front-end.}
    \label{fig:mockup_front-end_append}
\end{figure}