I'm trying to make two rules of different length (fatness) directly under each other, something like:
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Where = is a fatter line than -. The vertical space between the two should be 1mm. However this doesn't work:
\rule{\textwidth}{1mm}
\vspace{1mm}
\rule{\textwidth}{3mm}
The lines are way more than 1mm separated. How can I get this working?

