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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def copy_resources_to_log_dir(log_dir):
 """Copies the necessary static assets to the log_dir and returns the path of the main css file."""

        css_path = resource_filename(Requirement.parse("egat"), "/egat/data/default.css")
        header_path = resource_filename(Requirement.parse("egat"), "/egat/data/egat_header.png")
        shutil.copyfile(css_path, log_dir + "/style.css")
        shutil.copyfile(header_path, log_dir + "/egat_header.png")

        return log_dir + os.sep + "style.css"