Trying to reproduce your problem (you should have given a MWE), I start with:
\documentclass{moderncv}
\usepackage{lipsum}
\moderncvtheme[green]{casual}
\firstname{John}
\lastname{Doe}
%
\begin{document}
\maketitle
%
\section{Something or other}
\lipsum[1]
\lipsum[2]
\lipsum[3]
%
\section{Positions}
\cventry{DATE}{Position}{Company}{Location}{}{}
\cvlistitem{Role 1}
\cvlistitem{Role 2}
\cvlistitem{Role 3}
\cvlistitem{Role 4}
%
\end{document}
which produces:
Adding a \pagebreak before the positions' section gives:
Indeed the first page is ragged at the bottom. The reason is that the moderncv class chooses not to introduce vertical stretching lengths, neither between paragraphs (implicitly introduced by the \lipsum command here) nor at section headers and list items. Of course, you can introduce them yourself wherever you like:
\documentclass{moderncv}
\usepackage{lipsum}
\moderncvtheme[green]{casual}
\firstname{John}
\lastname{Doe}
%
\begin{document}
\maketitle
%
\section{Something or other}
\lipsum[1]\vfill
\lipsum[2]\vfill
\lipsum[3]\vfill
%
\pagebreak
%
\section{Positions}
\cventry{DATE}{Position}{Company}{Location}{}{}
\cvlistitem{Role 1}
\cvlistitem{Role 2}
\cvlistitem{Role 3}
\cvlistitem{Role 4}
%
\end{document}
and then you get something closer to what you want:
To do this automatically (i.e., to properly introduce stretching lengths between paragraphs, list items, section headers, etc.), I'm afraid you need to tweak the moderncv class quite a lot. Unless I'm missing something, it was clearly the author's intention to leave the pages ragged at the bottom. I suggest that you leave it like this, or you choose a different CV class that better suits your taste.
Best Answer
The space between the
\firstnameand\lastnameis set in\makecvtitle. Here's the code frommoderncvstylecasual.sty:The lines of interest are
where
\@firstnameis set with colourcolor2!50(50% ofcolor2) and\@lastnameis set with colourcolor2(full "strength" ofcolor2). Note the space between the two. That's a regular interword space; here's a visual when compilingtemplate.texunder thecasualstyle:The simplest way to adjust the spacing is to include any adjustment in the
\firstnamemacro itself:If you're using a cover letter as part of your resume, you may want to re-issue the
\firstnamethere in its correct/proper form, otherwise the adjustment will be used there as well.Here is a complete example from
template.tex(with an emphasized-.5emadjustment):