\section{Layout}

% columns: widths as fractions of \textwidth; [T] aligns their tops.
% \showdividers in main.tex outlines every column and row with its size.
\begin{frame}{Columns}
  \begin{columns}[T]
    \begin{column}{0.32\textwidth}
      \begin{block}{Column 1}
        \cmd{begin\{column\}\{0.32\textbackslash textwidth\}}
      \end{block}
    \end{column}
    \begin{column}{0.32\textwidth}
      \begin{block}{Column 2}
        Widths are shares of the text width.
      \end{block}
    \end{column}
    \begin{column}{0.32\textwidth}
      \begin{block}{Column 3}
        \texttt{[T]} aligns the tops.
      \end{block}
    \end{column}
  \end{columns}
\end{frame}

% rows: heights as fractions of the slide body; a row can hold columns,
% which makes a grid. \begin{row}[t]{0.55} aligns the row's content to its top.
\begin{frame}{Rows and grids}
  \begin{rows}
    \begin{row}{0.35}
      \centering A row takes a share of the slide height: \cmd{begin\{row\}\{0.35\}}
    \end{row}
    \begin{row}[t]{0.65}
      \begin{columns}[T]
        \begin{column}{0.48\textwidth}
          \FigurePlaceholder{3cm}{Row 2, column 1}
        \end{column}
        \begin{column}{0.48\textwidth}
          \FigurePlaceholder{3cm}{Row 2, column 2}
        \end{column}
      \end{columns}
    \end{row}
  \end{rows}
\end{frame}

% Side margins of the slide body for the frames after it (also in the
% preamble): \SetTextMargins{left}{right}. Here: narrow margins for one frame.
\SetTextMargins{0.3cm}{0.3cm}
\begin{frame}{Margins}
  \FigurePlaceholder{4cm}{\cmd{SetTextMargins\{0.3cm\}\{0.3cm\}} before this frame: wider body}
\end{frame}
\SetTextMargins{1cm}{1cm}