theorems and definitions boxes (numbering should be chapter-wise)

Question

I want to write both the theorems and definitions (numbering should be chapter-wise, like 2.1, 2.2 etc) in the form of the attached jpg file.

EDIT:

In the upper box only the title will come and within the box, the theorem/definition number will come. What to do?

I get a code in internet. I don't know how to modify it. Please help.

\documentclass{article}
\usepackage{amsmath}
\usepackage{cleveref}
\usepackage[most]{tcolorbox}
\newtcbtheorem{Theorem}{Theorem}{
  enhanced,
  sharp corners,
  attach boxed title to top left={
    yshifttext=-1mm
  },
  colback=white,
  colframe=blue!75!black,
  fonttitle=\bfseries,
  boxed title style={
    sharp corners,
    size=small,
    colback=blue!75!black,
    colframe=blue!75!black,
  } 
}{thm}
\newtcbtheorem[no counter]{Proof}{Proof}{
  enhanced,
  sharp corners,
  attach boxed title to top left={
    yshifttext=-1mm
  },
  colback=white,
  colframe=blue!25,
  fonttitle=\bfseries,
  coltitle=black,
  boxed title style={
    sharp corners,
    size=small,
    colback=blue!25,
    colframe=blue!25,
  } 
}{prf}

\begin{document}
\begin{Theorem}{}{fermat}
  No three positive integers \(a\), \(b\) and \(c\) satisfy the equation \(a^{n}
  + b^{n} = c^{n}\) for any integer greater than two.
\end{Theorem}
\begin{Proof}{Theorem \ref{thm:fermat}}{}
  The proof is easy, but too large to fit in this box.
\end{Proof}
\end{document}

Edit 2: Only the problem is in setting counter. Theorem should come 1.1, 1.2 ... and definition should come same as 1.1, 1.2 ....

\documentclass{book}
\usepackage{amsmath}
\usepackage[most]{tcolorbox}
\usepackage{cleveref}

\tcbset{theostyle/.style={
    enhanced,
    sharp corners,
    attach boxed title to top left={
      xshift=-1mm,
      yshift=-4mm,
      yshifttext=-1mm
    },
    top=1.5ex,
    colback=white,
    colframe=blue!75!black,
    fonttitle=\bfseries,
    boxed title style={
      sharp corners,
    size=small,
    colback=blue!75!black,
    colframe=blue!75!black,
  } 
}}

\newtcbtheorem[number within=chapter]{Theorem}{Theorem}{%
  theostyle
}{thm}

\newtcbtheorem[number within=chapter]{Definition}{Definition}{%
  theostyle
}{def}
\newenvironment{myTheorem}[2]{ \begin{Theorem}[adjusted title=#1]{}{#2} 
  \textbf{Theorem \thetcbcounter.} }{\end{Theorem}}
\newenvironment{myDefinition}[2]{ \begin{Theorem}[adjusted title=#1]{}{#2} 
  \textbf{Definition \thetcbcounter.} }{\end{Theorem}}
\begin{document}

\chapter{Foo chapter}

\begin{myDefinition}{ggggggggg}{ReadingTheManual}
  Reading the manual helps ;-)
\end{myDefinition}

\begin{myTheorem}{fffff}{fermat}
  No three positive integers \(a\), \(b\) and \(c\) satisfy the equation \(a^{n}
  + b^{n} = c^{n}\) for any integer greater than two.
\end{myTheorem}
\end{document}

Answer 1

\documentclass{book}
\usepackage{amsmath}
\usepackage{cleveref}
\usepackage[most]{tcolorbox}

\newtcbtheorem[number within=chapter]{Theorem}{}{
        enhanced,
        sharp corners,
        attach boxed title to top left={
            xshift=-1mm,
            yshift=-5mm,
            yshifttext=-1mm
        },
        top=1.5em,
        colback=white,
        colframe=blue!75!black,
        fonttitle=\bfseries,
        boxed title style={
            sharp corners,
            size=small,
            colback=blue!75!black,
            colframe=blue!75!black,
        } 
    }{thm}

\newtcbtheorem[number within=chapter]{Definition}{}{
        enhanced,
        sharp corners,
        attach boxed title to top left={
            xshift=-1mm,
            yshift=-5mm,
            yshifttext=-1mm
        },
        top=1.5em,
        colback=white,
        colframe=blue!75!black,
        fonttitle=\bfseries,
        boxed title style={
            sharp corners,
            size=small,
            colback=blue!75!black,
            colframe=blue!75!black,
        } 
    }{def}

\newenvironment{myTheorem}[2]{ \begin{Theorem}[adjusted title=#1]{}{#2} 
  \textbf{Theorem \thetcbcounter.} }{\end{Theorem}}

  \newenvironment{myDefinition}[2]{ \begin{Definition}[adjusted title=#1]{}{#2} 
  \textbf{Definition \thetcbcounter.} }{\end{Definition}}

\begin{document}
\chapter{Foo}
\begin{myTheorem}{Fermats Last Theorem}{thm:FermatsLastTheorem}
    No three positive integers \(a\), \(b\) and \(c\) satisfy the equation \(a^{n} + b^{n} = c^{n}\) for any integer greater than two.
\end{myTheorem}
\begin{myDefinition}{Reading the Manual}{def:ReadingTheManual}
  Reading the manual helps ;-)
\end{myDefinition}
\begin{myDefinition}{Definition}{def:Definition}
  A statement of the meaning of a word, phrase, or term, as in a dictionary entry.
\end{myDefinition}
\begin{myTheorem}{Pythagoras Theorem}{thm:PythagorasTheorem}
    In a right angled triangle: the square of the hypotenuse is equal to the sum of the squares of the other two sides.
\end{myTheorem}
\end{document}

Answer 2

Use the number within=chapter 'init' option of the \newtcbtheorem macro to apply chapter-wise counting of theorems defined with this macro. (See sections 5 and 16 of the tcolorbox manual for more information on the init option.)

The box style can be changed by using the xshift and yshift keys of attach boxed title to top left.

\documentclass{book}
\usepackage{amsmath}
\usepackage[most]{tcolorbox}
\usepackage{cleveref}

\tcbset{theostyle/.style={
    enhanced,
    sharp corners,
    attach boxed title to top left={
      xshift=-1mm,
      yshift=-4mm,
      yshifttext=-1mm
    },
    top=1.5ex,
    colback=white,
    colframe=blue!75!black,
    fonttitle=\bfseries,
    boxed title style={
      sharp corners,
    size=small,
    colback=blue!75!black,
    colframe=blue!75!black,
  } 
}}

\newtcbtheorem[number within=chapter]{Theorem}{Theorem}{%
  theostyle
}{thm}

\newtcbtheorem[number within=chapter]{Definition}{Definition}{%
  theostyle
}{def}


\begin{document}

\chapter{Foo chapter}

\begin{Definition}{}{ReadingTheManual}
  Reading the manual helps ;-)
\end{Definition}

\begin{Theorem}{}{fermat}
  No three positive integers \(a\), \(b\) and \(c\) satisfy the equation \(a^{n}
  + b^{n} = c^{n}\) for any integer greater than two.
\end{Theorem}
\end{document}