html_src = html_src.replace(css_marker, css_marker+custom_css, 1)
title_marker = '<title>'
html_src = html_src.replace(title_marker, title_marker + 'Rust-101: ', 1)
html_src = html_src.replace(css_marker, css_marker+custom_css, 1)
title_marker = '<title>'
html_src = html_src.replace(title_marker, title_marker + 'Rust-101: ', 1)