Source

beamer / beamerthemeplain.sty

\ProvidesPackage{beamerthemeplain}[2003/09/17 ver 0.1]
\NeedsTeXFormat{LaTeX2e}[1995/12/01]

% Copyright 2003 by Till Tantau <tantau@cs.tu-berlin.de>.
%
% This program can be redistributed and/or modified under the terms
% of the LaTeX Project Public License Distributed from CTAN
% archives in directory macros/latex/base/lppl.txt.

                                % Title page  
\usetitlepagetemplate{
  \vbox{}
  \vfill
  \begin{centering}
    \Large\structure{\textrm{\textit{{\inserttitle}}}}
    \vskip1em\par
    \normalsize\insertauthor\vskip1em\par
    {\scriptsize\insertinstitute\par}\par\vskip1em
    \insertdate\par\vskip1.5em
    \inserttitlegraphic
  \end{centering}
  \vfill
  }

                                % Frametitles
\useframetitletemplate{%
  \vskip1.5em
  {\leftskip-\beamer@leftmargin plus1fill\advance\leftskip by0.3cm%
   \rightskip-\beamer@rightmargin plus1fill\advance\rightskip by0.3cm\leavevmode
    \color{structure}\Large\textrm{\textit{{\insertframetitle}}}\par}
  }

                                % Sections in headline
\usesectionheadtemplate
{\color{structure}\tiny\insertsectionhead}
{\color{structureshaded}\tiny\insertsectionhead}

                                % Entries in table of contents
\usetemplatetocsection
{{\large\color{structure}\textrm{\textit{{\inserttocsection}}}}}
{{\large\color{structureshaded}\textrm{\textit{{\inserttocsection}}}}}

                                % Entries in table of contents
\usetemplatetocsubsection
{\leavevmode\leftskip=1.5em\color{black}\inserttocsubsection\par}
{\leavevmode\leftskip=1.5em\color{shaded}\inserttocsubsection\par}

                                % Head
\useheadtemplate{}

                                % Footline
\usefoottemplate{}

\def\logo#1{%
  \def\insertlogo{#1}%
  \usefoottemplate{\hfill\insertlogo}
  }

                                % Background
\usebackgroundtemplate{}

                                % Blocks
\useblocktemplate{\medskip{\color{structure}\large\textrm{\textsc{\insertblockname}}}\par}{\medskip}
\usealertblocktemplate{\medskip{\alert{\large\textrm{\textsc{\insertblockname}}}}\par}{\medskip}
\useexampleblocktemplate{\medskip\begingroup\color{darkgreen}{\large\textrm{\textsc{\insertblockname}}}\par}{\endgroup\medskip}

                                % Itemize
\useitemizeitemtemplate{\tiny\raise1.5pt\hbox{\color{structure}$\blacktriangleright$}}
\usesubitemizeitemtemplate{\tiny\raise1.5pt\hbox{\color{structure}$\blacktriangleright$}}