Build a Ghost-Number Section Heading in LaTeX

Hi, I'm KKTeX. I publish LaTeX packages on CTAN and build typesetting tools for education in Japan.

In many Japanese mathematics books, a section heading is not merely larger text. It is page architecture: number, hierarchy, and reading rhythm.

This article makes one heading with a pale “ghost number” and a restrained blue rule.

The drawing

\usepackage{tikz}

\definecolor{qink}{HTML}{0F172A}         % slate-900
\definecolor{qline}{HTML}{CBD5E1}        % slate-300
\definecolor{qaccent}{HTML}{38BDF8}      % sky-400
\definecolor{qaccentDark}{HTML}{0369A1}  % sky-700

\newcounter{booksection}

\NewDocumentCommand{\BookSection}{m}{%
  \refstepcounter{booksection}%
  \par\medskip\noindent
  \begin{tikzpicture}
    \useasboundingbox
      (0,0) rectangle (\linewidth,-2.7\baselineskip);

    \node[
      anchor=base west,text=qline,
      font=\sffamily\bfseries
            \fontsize{40pt}{40pt}\selectfont
    ] at (0,-1.55\baselineskip)
      {\ifnum\value{booksection}<10 0\fi
       \arabic{booksection}};

    \node[
      anchor=base west,text=qaccentDark,
      font=\sffamily\scriptsize\bfseries
    ] at (26mm,-.55\baselineskip) {LESSON};

    \node[
      anchor=base west,text=qink,
      font=\sffamily\Large\bfseries
    ] at (26mm,-1.45\baselineskip) {#1};

    \draw[qaccent,line width=.8pt]
      (26mm,-2.2\baselineskip)
      -- (.78\linewidth,-2.2\baselineskip);
    \draw[qline,line width=.8pt]
      (.78\linewidth,-2.2\baselineskip)
      -- (\linewidth,-2.2\baselineskip);

    \foreach \x in {0,1,2}{
      \fill[qaccentDark]
        ([xshift=-\x*3.4mm]\linewidth,
          -.55\baselineskip)
        circle[radius=1.2pt];
    }
  \end{tikzpicture}
  \par\smallskip
}

Use it once per section:

\BookSection{Completing the Square}

Compilation note: my figure source uses ltjsarticle with LuaLaTeX, matching my Japanese material workflow. The heading itself also works inside an ordinary article document.

The page gets a clear hierarchy, ordered here by visual importance:

1. The dark title carries meaning.
2. The small LESSON label identifies the component.
3. The pale number helps navigation without competing for attention.

The component-system idea comes from my private book-production toolkit, kkbookmaker, but the ghost-number design is new for this article.

Why the number is large but pale

Japanese reference books often expose structure more aggressively than ordinary prose books. A student may jump between an example, its solution, a related exercise, and a later review page. Strong numbering helps that movement, but a dark oversized number would compete with the mathematics.

The ghost number solves both problems: it is large enough to find quickly and light enough to sit behind the reading hierarchy. The title remains the darkest element, while the small LESSON label tells the reader what kind of marker this is. This is navigation, not decoration.

Two tools from the same desk

Disclosure: I'm promoting both projects in this section.

Evolton turns a photo or screenshot of a mathematics problem into a reference-book-style worked-solution PDF. Its database lets you browse university entrance-exam material by university, faculty, and year.

MathHover opens a LaTeX input panel beside your cursor, then pastes the finished formula into your current app. It is free to use and requires no account.

Next in the series: Japanese-born CTAN packages for answer fields, Kanbun, underlining, and more.