Dockerfile that creates a bad PDF

Dockerfile

FROM python:3.6-slim-stretch

RUN \
	echo "weasyprint dependencies" \
	&& apt-get update \
	&& apt-get install -y --no-install-recommends \
		libcairo2 \
		libpango1.0-0 \
		libpangocairo-1.0.0 \
		libgdk-pixbuf2.0-0 \
		shared-mime-info

RUN \
	echo "imagemagick dependencies" \
	&& apt-get update \
	&& apt-get install -y --no-install-recommends \
		ghostscript \
		imagemagick

RUN pip install weasyprint==0.41

COPY letter.html .

RUN weasyprint letter.html letter.pdf

RUN convert -density 300 -depth 8 -quality 85 letter.pdf letter.png