为什么此代码会在两条彩色线之间产生一条空白行？

Question

\documentclass[12pt,portrait]{article}

\usepackage{graphicx}
%\usepackage{blindtext}
\usepackage{hyperref} %--- per i link
\usepackage{multicol} %------ per formattare pagine a più colonne
\usepackage[T1]{fontenc}
\usepackage{tcolorbox} %--- per le caselle di testo I pagina
\usepackage[percent]{overpic}
%------------------------------------
\setlength\textwidth{267mm}
\setlength\paperwidth{300mm}
\setlength\oddsidemargin{-1cm}
%-------------------------------
\usepackage{ebgaramond-maths}%----- uso font garamond
\usepackage[T1]{fontenc}%----- uso font garamond
%\pagestyle{empty}
\usepackage[margin=0pt]{geometry}
\usepackage{showframe}
%------ set colori del link
\hypersetup{
    colorlinks=true,
    linkcolor=black,
    filecolor=magenta,      
    urlcolor=cyan,
    pdftitle={Overleaf Example},
    pdfpagemode=FullScreen,
    }

 %----- dimensione della pagina ------
 \geometry{
 a3paper,
 total={297mm,420mm},
 left=15mm,
 top=15mm,
 right=15mm,
 bottom=0mm,
 }


\tcbset{colback=white!5!!,colframe=red!15!white!60!,size=small,
fonttitle=\bfseries,width=0.333\textwidth,box align=top,height=7cm,nobeforeafter}

\begin{document}
%----  inserimento banner --------
    \noindent\includegraphics [height=40mm,width=267mm]{pannello_blu_corto.png}
        
        \nointerlineskip
      \noindent\includegraphics[height=10mm,width=267mm]{filo_celeste_basso.png}



\noindent
%------ I box ---------------
\nointerlineskip
   \begin{tcolorbox}[adjusted title=\hyperlink{1_1}{bla bla bla},halign=justify]
bla bla bla bla bla
    \end{tcolorbox} %------fine I box --------
    \begin{tcolorbox}[adjusted title=\hyperlink{1_1}{xyzxyz xyz xyz xy},halign=justify]
xyz xyz xyz xyz xyz xyz
        \end{tcolorbox}
  \begin{tcolorbox}[adjusted title=\hyperlink{1_1}{xyzxyz xyz xyz xy},halign=justify]
xyz xyz xyz xyz xyz xyz
    \end{tcolorbox}\\
    \begin{tcolorbox}[adjusted title=left,halign=left]

Answer 1

这些不是浮动元素，而是（我认为）页面设计的一部分，因此只需直接放置它们即可，而不是放在figure

\documentclass[landscape]{article}
\usepackage{graphicx}
\setlength\textwidth{267mm}
\setlength\paperwidth{300mm}
\setlength\oddsidemargin{-1cm}
\begin{document}

\begin{center}
   \includegraphics [height=40mm,width=267mm]{example-image-a}

    \nointerlineskip
    \includegraphics[height=40mm,width=267mm]{example-image-b}
\end{center}
\end{document}