sphinx, conf.py, generate nice looking PDF file and reading the PREAMBLE latex-styling.tex

conf.py

# -- Options for LaTeX output ------------------------------------------------
f = open('latex-styling.tex', 'r+')
PREAMBLE = f.read()

latex_elements = {
    # https://www.sphinx-doc.org/en/master/latex.html
    # 'classoptions': ',openany,twoside',
    'classoptions': ',openany',

    # 'babel' : '\\usepackage[french]{babel}',
    # The paper size ('letterpaper' or 'a4paper').
    #
    'papersize': 'a4paper',

    # The font size ('10pt', '11pt' or '12pt').
    #
    'pointsize': '10pt',

    # Additional stuff for the LaTeX preamble.
    #
    # 'preamble': '',
    'preamble': PREAMBLE,
    'maxlistdepth': '10',
    # Latex figure (float) alignment
    #
    # 'figure_align': 'htbp',
    'figure_align': 'H',
}