def render_longest_xsection_to_svg(mesh, plane, filename, look=None, **kwargs):
    """
    Rectangle of specified height and width along the plane normal,
    with given up vector, centered on the plane's reference point.

    When width or height is not provided, automatically set based on the data
    with 10% padding.
    """
    from .mesh import longest_xsection
    from .svg import write_polyline_3d
    if look is None:
        look = plane.normal
    xs = longest_xsection(mesh, plane)
    write_polyline_3d(polyline=xs, filename=filename, look=look, **kwargs)
    return xs
