I'm trying to redraw a kernel scheme diagram for a university lecture note. This is how far I got:

```
\documentclass{article}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[magyar]{babel}

\usepackage{tikz}
\usetikzlibrary{positioning,fit}

\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}

\begin{document}

\begin{tikzpicture}[font=\sffamily]
    \tikzstyle{title}=[rectangle]
    \tikzstyle{wrapper}=[anchor=west, draw]
    \tikzstyle{bigblock}=[rectangle, minimum width=10cm, minimum height=1cm, anchor=west, draw]
    \tikzstyle{Nbigblock}=[rectangle, minimum width=10cm, minimum height=1cm, anchor=north, draw]
    \tikzstyle{Sbigblock}=[rectangle, minimum width=10cm, minimum height=1cm, anchor=south, draw]
    \tikzstyle{medblock}=[rectangle, minimum width=6cm, minimum height=1cm, anchor=south, draw]
    \tikzstyle{smallblock}=[rectangle, minimum width=3cm, minimum height=1cm, anchor=west, draw]

    \node (kernel) [title] {Kernel};
    \node (syscalls) [bigblock, below=of kernel] {Rendszerhívások};
    \node (filesystems) [smallblock, below=of syscalls.west] {Fájlrendszerek};
    \node (networklayer) [smallblock, below=of filesystems] {Hálózati réteg};

    \node (processhandling) [title,below=of syscalls.east] {Processzkezelés};
    \node (scheduler) [smallblock, below=of processhandling] {Ütemező};
    \node (memhandling) [smallblock, below=of scheduler] {Memóriakezelés};
    \node (IPC) [smallblock, below=of memhandling] {IPC};

    \node (processhandlingwrapper) [wrapper, fit={(processhandling) (scheduler) (memhandling) (IPC)}] {};

    \node (periphhandling) [bigblock, below=of processhandlingwrapper.south east] {Perifériák kezelése};

    \node (kernelwrapper) [wrapper, fit={(kernel) (filesystems) (syscalls) (networklayer) (processhandling) (periphhandling)}] {};

    \node (hardver) [below=of kernelwrapper.south, Nbigblock] {Hardver};

    \node (syslibs) [above=of kernelwrapper, medblock] {Rendszerkönyvtárak};

    \node (usrprocesses) [above=of syslibs, Sbigblock] {Felhasználói processzek};
\end{tikzpicture}

\end{document}

```

On the left you can see the diagram I want to redraw using TikZ, on the right side is my approach, where you can see wrong positioning and the lack of arrows.

![Kernel scheme](https://i.stack.imgur.com/gadNW.png) ![Kernel scheme](https://i.stack.imgur.com/0jCPy.png)

Could you help me correct the positioning and draw the arrows to the right places? Thanks!