How to make text inside tcolorbox also transparent as overlay?

Question

I want to have a slide with some text in a box at the top, and on the next slide, this box - and the text within - become transparent to some opacity i specify. The tcolorbox is crucial to me because i want the colors and shape of the box to be consistent. I am currently trying out \uncover, but it doesn't make text transparent.

I also have another question, which is, how do I ensure that there's not too much space after tcolorbox? It doesn't show that much in this example, but I just want to be able to control the spacing between tcolorbox and the next line.

\documentclass{beamer}
\mode<presentation>
{
%  \usetheme{default}      % or try Darmstadt, Madrid, Warsaw, ...
%  \usecolortheme{default} % or try albatross, beaver, crane, ...
%  \usefonttheme{default}  % or try serif, structurebold, ...
  \setbeamertemplate{navigation symbols}{}
  \setbeamertemplate{caption}[numbered]
}

\usepackage{tcolorbox}

\usepackage{verbatim}
\usepackage{tikz}
\usepackage{booktabs}
\usetikzlibrary{matrix,overlay-beamer-styles}

\definecolor{myorange}{rgb}{.98, .59, .01}
\definecolor{myyellow}{rgb}{1, .78, .33}
\definecolor{myblue}{rgb}{.18, .63, .78}
%%%%%%%%%
\usetikzlibrary{calc}
\definecolor{pbblue}{HTML}{0A75A8}% color for the progress bar and the circle

\makeatletter
\def\progressbar@progressbar{} % the progress bar
\newcount\progressbar@tmpcounta% auxiliary counter
\newcount\progressbar@tmpcountb% auxiliary counter
\newdimen\progressbar@pbht %progressbar height
\newdimen\progressbar@pbwd %progressbar width
\newdimen\progressbar@rcircle % radius for the circle
\newdimen\progressbar@tmpdim % auxiliary dimension

\progressbar@pbwd=\linewidth
\progressbar@pbht=1pt
\progressbar@rcircle=2.5pt

% the progress bar
\def\progressbar@progressbar{%

    \progressbar@tmpcounta=\insertframenumber
    \progressbar@tmpcountb=\inserttotalframenumber
    \progressbar@tmpdim=\progressbar@pbwd
    \multiply\progressbar@tmpdim by \progressbar@tmpcounta
    \divide\progressbar@tmpdim by \progressbar@tmpcountb

  \begin{tikzpicture}
    \draw[pbblue!30,line width=\progressbar@pbht]
      (0pt, 0pt) -- ++ (\progressbar@pbwd,0pt);

    \filldraw[pbblue!30] %
      (\the\dimexpr\progressbar@tmpdim-\progressbar@rcircle\relax, .5\progressbar@pbht) circle (\progressbar@rcircle);

    \node[draw=pbblue!30,text width=3.5em,align=center,inner sep=1pt,
      text=pbblue!70,anchor=east] at (0,0) {\insertframenumber/\inserttotalframenumber};
  \end{tikzpicture}%
}

\addtobeamertemplate{headline}{}
{%
  \begin{beamercolorbox}[wd=\paperwidth,ht=4ex,center,dp=1ex]{white}%
    \progressbar@progressbar%
  \end{beamercolorbox}%
}
\makeatother
%%%%%%%%%%%
\begin{document}
\section{Proofs}
\begin{frame}[t]{title }
\setbeamercovered{transparent}%

\uncover<1>{\begin{tcolorbox}[hbox, left = 0.1 mm, right=0.1 mm, top = 0.4mm, bottom = 0.4mm]
Main idea
\end{tcolorbox}}

\uncover<2>{asdfasdf}
\end{frame}


\end{document}

Answer 1

tcolorbox comes with a lot of beamer support, see section 13 Beamer Support of manual v4.30. In particle, there is a hide key, which can be used here. One then can specify what "hide" means with

\tcbset{beamer hidden/.style={}}

Here is an example.

\documentclass{beamer}
\mode<presentation>
{
%  \usetheme{default}      % or try Darmstadt, Madrid, Warsaw, ...
%  \usecolortheme{default} % or try albatross, beaver, crane, ...
%  \usefonttheme{default}  % or try serif, structurebold, ...
  \setbeamertemplate{navigation symbols}{}
  \setbeamertemplate{caption}[numbered]
}

\usepackage[skins]{tcolorbox}

\usepackage{verbatim}
\usepackage{tikz}
\usepackage{booktabs}
\usetikzlibrary{matrix,overlay-beamer-styles}

\definecolor{myorange}{rgb}{.98, .59, .01}
\definecolor{myyellow}{rgb}{1, .78, .33}
\definecolor{myblue}{rgb}{.18, .63, .78}
%%%%%%%%%
\usetikzlibrary{calc}
\definecolor{pbblue}{HTML}{0A75A8}% color for the progress bar and the circle

\makeatletter
\def\progressbar@progressbar{} % the progress bar
\newcount\progressbar@tmpcounta% auxiliary counter
\newcount\progressbar@tmpcountb% auxiliary counter
\newdimen\progressbar@pbht %progressbar height
\newdimen\progressbar@pbwd %progressbar width
\newdimen\progressbar@rcircle % radius for the circle
\newdimen\progressbar@tmpdim % auxiliary dimension

\progressbar@pbwd=\linewidth
\progressbar@pbht=1pt
\progressbar@rcircle=2.5pt

% the progress bar
\def\progressbar@progressbar{%

    \progressbar@tmpcounta=\insertframenumber
    \progressbar@tmpcountb=\inserttotalframenumber
    \progressbar@tmpdim=\progressbar@pbwd
    \multiply\progressbar@tmpdim by \progressbar@tmpcounta
    \divide\progressbar@tmpdim by \progressbar@tmpcountb

  \begin{tikzpicture}
    \draw[pbblue!30,line width=\progressbar@pbht]
      (0pt, 0pt) -- ++ (\progressbar@pbwd,0pt);

    \filldraw[pbblue!30] %
      (\the\dimexpr\progressbar@tmpdim-\progressbar@rcircle\relax, .5\progressbar@pbht) circle (\progressbar@rcircle);

    \node[draw=pbblue!30,text width=3.5em,align=center,inner sep=1pt,
      text=pbblue!70,anchor=east] at (0,0) {\insertframenumber/\inserttotalframenumber};
  \end{tikzpicture}%
}

\addtobeamertemplate{headline}{}
{%
  \begin{beamercolorbox}[wd=\paperwidth,ht=4ex,center,dp=1ex]{white}%
    \progressbar@progressbar%
  \end{beamercolorbox}%
}
\makeatother
%%%%%%%%%%%
\tcbset{
beamer hidden/.style={opacityframe=0.1,opacityback=0.1,
opacitybacktitle=0.1,opacitytext=0.1}, }
\begin{document}
\section{Proofs}
\begin{frame}[t]{title }
\setbeamercovered{transparent}%

\begin{tcolorbox}[hbox, left = 0.1 mm, right=0.1 mm, 
top = 0.4mm, bottom = 0.4mm,hide=<2->]
Main idea
\end{tcolorbox}

\uncover<2>{asdfasdf}
\end{frame}
\end{document}

There are many more options to achieve similar results.

ADDENDUM: For the question in the comments you may use an overprint environment.

\documentclass{beamer}
\setbeamercovered{transparent}%
\begin{document}
\begin{frame}[t]
\frametitle{Without overprint}
\onslide<1>
Einstein said that \[E=mc^2\]
\onslide<2>
test

abc
\end{frame}

\begin{frame}[t]
\frametitle{With overprint}
\begin{overprint}
\onslide<1>
Einstein said that \[E=mc^2\]
\onslide<2>
test
\end{overprint}

abc
\end{frame}
\end{document}