Fix print CSS layout
Move first lecture to subdirectory
Add PDF version of first lection

Printed in PDF in Firefox and cut with

gs \
  -o lecture_01_introduction.pdf \
  -sDEVICE=pdfwrite \
  -c "[/CropBox [59 416 536 782] /PAGES pdfmark" \
  -f lecture_01_introduction_orig.pdf

Use this box to cut with borders:
/CropBox [55 410 540 788]