[Tex/LaTex] Too large top margin at the new page

Question

Here is my code:

\documentclass[a4paper,13pt,russian]{extreport}

\usepackage{extsizes}
\usepackage[utf8]{inputenc}
\usepackage[T2A]{fontenc}
\usepackage[russian]{babel}

\usepackage{vmargin}
\setmarginsrb{3cm}{2.5cm}{2cm}{2cm}{11pt}{1.8cm}{11pt}{10mm}

\begin{document}
\newpage
Hello
\end{document}

And here is the result:

The question is, why is the margin before text so large? Is there a way to reduce it?

Answer 1

You should use geometry instead of vmargin. But still, to answer why it happens, the macro \setmarginsrb has these arguments

\setmarginsrb{left margin}{top margin}{right margin}{bottom margin}{head height}{head sep}{foot height}{foot skip}

When you say

\setmarginsrb{3cm}{2.5cm}{2cm}{2cm}{11pt}{1.8cm}{11pt}{10mm}

You are specifying a top margin of 2.5cm along with head height 11pt, head sep of 1.8cm so the first text line occurs at a distance of 2.5cm+11pt+1.8cm from the top of the paper. Here is a demo of the same using showframe package.

Hope things are clear now. If you want to escape from these troubles, just use

\usepackage[left=3cm,right=2cm,top=2.5cm,bottom=2cm]{geometry}