|C{0.2}L{0.2}R{0.2}L{0.4}|     ->  C{0.2}|L{0.2}|R{0.2}|L{0.4}
|C{0.2}|L{0.2}|R{0.2}|L{0.4}|  ->  C{0.2}|L{0.2}|R{0.2}|L{0.4}
C{0.25}L{0.75}                 ->  C{0.25}|L{0.75}

documentclass{article}

usepackage[table]{xcolor}      % Provides coloring for tables and text
usepackage{tabularx}           % Customized table formatting
RequirePackage{environ}        % Used to define custom table environment

% Define table related commands and properties
definecolor{greyblue}{rgb}{0.6353,0.6863,0.7686} % Define a color used in the tables
newcommandsetrow[1]{gdefrowmac{#1}#1ignorespaces} % Used for making a row bold
newcommandclearrow{globalletrowmacrelax} clearrow % Used for clearing a row formatting
newcolumntype{C}[1]{>{hsize=#1hsizerowmaccenteringarraybackslash}X} % Centered column, input is relative width of page
newcolumntype{L}[1]{>{hsize=#1hsizerowmacraggedrightarraybackslash}X} % Left-aligned column, input is relative width of page
newcolumntype{R}[1]{>{hsize=#1hsizerowmacraggedleftarraybackslash}X} % Left-aligned column, input is relative width of page

% Defines an environment to create a table in the document according to
% a common formatting. This uses the environ package.
NewEnviron{doctable}[4]{
    begin{table}[!htbp]
        centering
        rowcolors{2}{black!5}{black!15}
        begin{tabularx}{#3linewidth}{#4<{clearrow}}%
            hline
            rowcolor{greyblue} setrow{bfseries} % Make the header row bold and colored grey-blue
            BODY
            hline
        end{tabularx}
        caption{#2}
        label{#1}
    end{table}
}

begin{document}
    begin{doctable}
        {tbl:label}
        {Table Caption}
        {1} { C{0.25}L{0.75} }
        Heading 1 & Heading 2 \
        Text 1    & Text 2    \
    end{doctable}
end{document}