# Getting shaded headline flush with top of slide with outertheme tree in beamer

I'm using the following code (roughly) to install a left-right shaded background behind a beamer headline. The contents of the headline is set using the outertheme tree. The shading method is based roughly on that for Singapore. The problem is that I have a line of light green at the very top of the slide, whereas I would like the dark green to go all the way to the top.

\PassOptionsToPackage{rgb}{xcolor}
\documentclass{beamer}
\definecolor{acol}{rgb}{.5,1,.5}
\definecolor{bcol}{rgb}{.1,.6,.2}
\colorlet{bcol1}{bcol!25!black}
\makeatletter
\useoutertheme{tree}
{%
color(0cm)=(bcol1);
color(\paperwidth)=(acol)%
}
\makeatother
\begin{document}

\title{Title}
\section{A Section}
\subsection{A Subsection}

\begin{frame}{A Frame}{A Subframe}
Some text
\end{frame}

\end{document}


Presumably I've miscalculated or used the wrong values somewhere but every time I push something, something or other pushes back and I just can't seem to get it right. (Probably because I'm mesmerised, as usual, by the maze of beamer's code.)

Any hint would be much appreciated!

• No time to dig in for a proper answer now but if you use \addtoheadtemplate{\vskip 2.5pt... the upper line goes to the top: picture here – user11232 Sep 29 '14 at 0:30
• @HarishKumar Thanks very much! That works perfectly. If you would like to write a proper answer (ideally explaining how to figure out the right value), I'd be happy to accept/up-vote it. (I'm hoping to accept an answer which explains but I'm happy to up-vote an answer which just works in the meantime!) – cfr Sep 29 '14 at 1:10
• @HarishKumar I'm now even more puzzled. When I used these slides today, it turns out there is a light vertical line at the far left of the slide. So clearly I'm missing something here! However, I cannot see it in Okular at all. – cfr Sep 29 '14 at 20:48
• There's a question related to this somewhere... I'm almost sure I've seen this issue asked about but I can't remember... If I zoom in and then return to fit-page view, I see the pale vertical line - or, more, a wide rectangle - for a moment before the shading covers it over. Something like this came up - somebody asked. If anybody has a clue where that question is, please let me know! – cfr Sep 29 '14 at 20:54
• Looks so. I forgot yesterday. Later today when I get some time, I will check it out. – user11232 Sep 29 '14 at 23:20

I get an error with the MWE you provided. It's given in this line, saying that \dimexpr can not be used in vertical mode:

\pgfdeclarehorizontalshading{beamer@headfade}{\dimexpr5.4375ex+3pt}


I just removed it, and it works for me (there's no line at the top):

\pgfdeclarehorizontalshading{beamer@headfade}{5.4375ex+3pt}


\PassOptionsToPackage{rgb}{xcolor}
\documentclass{beamer}
\definecolor{acol}{rgb}{.5,1,.5}
\definecolor{bcol}{rgb}{.1,.6,.2}
\colorlet{bcol1}{bcol!25!black}
\makeatletter
\useoutertheme{tree}
{%
color(0cm)=(bcol1);
color(\paperwidth)=(acol)%
}
\makeatother
\begin{document}

\title{Title}
\section{A Section}
\subsection{A Subsection}

\begin{frame}{A Frame}{A Subframe}
Some text
\end{frame}

\end{document}


• That's odd. It compiles fine here. Moreover, removing it does not resolve the issue for me. I get exactly the same visual result. – cfr Sep 29 '14 at 1:05
• Just added a picture and the full code I've used. I'm using MiKTeX and compiling with pdflatex. I don't know if that could make the difference. – U.Martinez-Corral Sep 29 '14 at 1:14
• I'm using pdflatex but I'm using TeX Live. I can compile either way. With exactly the same results either way. I don't doubt it is different for you, but this is not, unfortunately, of help to me. Thanks anyway. – cfr Sep 29 '14 at 1:23