# Beamer - Modifying the headline

With beamer, I use the theme Montpellier, a sober theme giving basic navigational hints.

\usetheme{Montpellier}
\useinnertheme{default}
\useoutertheme{default}
\usecolortheme{default}
\usefonttheme{professionalfonts}


I would like to reduce the width of the separation lines. Can you help me to perform that task?

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Hi, welcome to TeX.SX. Note that you can use backticks  to mark inline code as well as package names. It's not necessary to begin your question with a greeting or have a closing line. – Martin Scharrer Apr 2 '11 at 12:37
@MArtin Scharrer: Ok, thank for the advice – Marco Apr 2 '11 at 12:59
You are aware, I am sure, that your proof is incorrect? q+1 does not need to be prime, however it is not divisible by any known primes, and thus only divisible by unknown primes. – Mikael Vejdemo-Johansson Apr 2 '11 at 15:40
@Mikael Vejdemo-Johansson: Oh, actually, this is not my proof. The picture comes from a user guide and I have chosen it to illustrate the theme. But since q+1 is larger than 1 it is divisible by some prime k (Fundamental theorem of Arithmetic). This prime k must be one the primes that is less than or equal to p, by our assumption that p is the largest prime. So k divides the q. Finally, since k divides both q+1 and q, it also divides 1, which is impossible. ;-) – Marco Apr 2 '11 at 16:29

I'm not a great expert with Beamer but I think you need to change the lines in the file : beamerouterthemetree.sty

\begin{beamercolorbox}[wd=\paperwidth,colsep=1.5pt]{upper separation line head}
\end{beamercolorbox}
...
`