整个文档周围的框架

Question

我正在尝试将 tcolorbox 放在整个文档（每页）周围。我正在观看 YouTube 上的 Math Partner 教程并正确输入所有代码，但没有框跨越我的页面。代码如下，有人知道为什么框架不起作用吗？

\documentclass[a4paper,addpoints,12pt]{exam}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{xcolor}
\usepackage[most]{tcolorbox}
\usepackage{tikz}
\usepackage[utf8]{inputenc}
\usepackage[left=12mm,right=15mm,top=20mm,bottom=30mm]{geometry}

%reformat question and parts 
\renewcommand{\questionlabel}{\textbf{\thequestion).}}
\renewcommand{\partlabel}{\textbf{\thepartno).}}



\begin{document}
    \begin{tcolorbox}[%
        enhanced,
        breakable,
        frame hidden,
        overlay broken={
            \draw[line width=0.5mm, gray,rounded corners]
            (frame.north west)rectangle (frame.south east);},
        colback=white,height fixed for=all]{}
            

\pointsdroppedatright
\marginpointname{ \points}
\setlength{\rightpointsmargin}{25mm}
\pointformat{\bfseries\boldmath[\themarginpoints]}
    \begin{questions}
        \question[4]Find the equation of the tangent to the curve $y=4x^2-5x+7$ \droppoints
            
            \vspace*{1in}
                \answerline
                
                
                
        
                \rule{\textwidth}{1.25pt}
        \question[2] Expand $(x-2)(x+3)$ \droppoints
            \vspace*{1in}
        
        \question Solve 
            \begin{parts}
                \part[2] $3(x-2)=1$ \droppoints
                    \vspace*{1in}
                \part[4] $5x-4=\frac{1}{2}$ \droppoints
            \end{parts}

\question Simplify 
    \end{questions}
    
    \end{tcolorbox}
    
\end{document}