设置在投影机上，如何在脚线上获得相同的阴影？乳胶新手，注意希腊字符

Question

\documentclass{beamer}

\setbeamertemplate{navigation symbols}{}




\usepackage[utf8]{inputenc}
\usepackage[english,greek]{babel} 
\usepackage{alphabeta}
\usepackage{multicol}
\newcommand{\en}{\selectlanguage{english}}
\newcommand{\gr}{\selectlanguage{greek}}
\author{\textlatin{author}}
\usepackage{array,amsmath}
\usepackage{amsthm}

\definecolor{UniBlue}{RGB}{83,121,170}
\definecolor{frame}{RGB}{2,0,0}
\setbeamercolor*{frametitle}{fg=frame}


\useoutertheme{shadow}
\usepackage{tikz}
\usetikzlibrary{shadings}
\colorlet{titleleft}{cyan!75!black}
\colorlet{titleright}{UniBlue}

\makeatletter
\pgfdeclarehorizontalshading[titleleft,titleright]{beamer@frametitleshade}{\paperheight}{%
    color(0pt)=(titleleft);
    color(\paperwidth)=(titleright)}
\makeatother






\title{}

\begin{document}


    \begin{frame}{\textlatin{frametitle}}

\end{frame}

\end{document}

Answer 1

复制脚线，阴影定义在https://tex.stackexchange.com/a/311829/36296：

\documentclass{beamer}

\setbeamertemplate{navigation symbols}{}




\usepackage[utf8]{inputenc}
\usepackage[english,greek]{babel} 
\usepackage{alphabeta}
\usepackage{multicol}
\newcommand{\en}{\selectlanguage{english}}
\newcommand{\gr}{\selectlanguage{greek}}
\author{\textlatin{author}}
\usepackage{array,amsmath}
\usepackage{amsthm}

\definecolor{UniBlue}{RGB}{83,121,170}
\definecolor{frame}{RGB}{2,0,0}
\setbeamercolor*{frametitle}{fg=frame}


\useoutertheme{shadow}
\usepackage{tikz}
\usetikzlibrary{shadings}
\colorlet{titleleft}{cyan!75!black}
\colorlet{titleright}{UniBlue}

\makeatletter
\pgfdeclarehorizontalshading[titleleft,titleright]{beamer@frametitleshade}{\paperheight}{%
    color(0pt)=(titleleft);
    color(\paperwidth)=(titleright)}
\makeatother

\setbeamercolor{author in head/foot}{parent=palette primary,bg=}
\setbeamercolor{title in head/foot}{parent=palette secondary,bg=}
\setbeamercolor{date in head/foot}{parent=palette tertiary,bg=}

\makeatletter
\setbeamertemplate{footline}
{
    \leavevmode%
    \setbox\beamer@tempbox=\hbox{%
        \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}%
            \usebeamerfont{author in head/foot}\insertshortauthor\expandafter\beamer@ifempty\expandafter{\beamer@shortinstitute}{}{~~(\insertshortinstitute)}
        \end{beamercolorbox}%
        \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{title in head/foot}%
            \usebeamerfont{title in head/foot}\insertshorttitle
        \end{beamercolorbox}%
        \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,right]{date in head/foot}%
            \usebeamerfont{date in head/foot}\insertshortdate{}\hspace*{2em}
            \insertframenumber{} / \inserttotalframenumber\hspace*{2ex} 
        \end{beamercolorbox}%
        }%
        \beamer@tempdim=\ht\beamer@tempbox%
        \advance\beamer@tempdim by 4pt%
        \begin{pgfpicture}{0pt}{0pt}{\paperwidth}{20pt}
            \pgfpathrectangle{\pgfpointorigin}{\pgfpoint{\paperwidth}{\beamer@tempdim}}
            \pgfusepath{clip}
            \pgftext[left,base]{\pgfuseshading{beamer@frametitleshade}}
        \end{pgfpicture}
        \vskip-\beamer@tempdim%
        \box\beamer@tempbox%    
}%
\makeatother




\title{}

\begin{document}


    \begin{frame}{\textlatin{frametitle}}

\end{frame}

\end{document}