Comment by threeducks

HTML to PNG:

    chromium --headless --disable-gpu --screenshot=output.png --window-size=1920,1080 --hide-scrollbars index.html

Also works great for HTML to PDF:

    chromium --headless --disable-gpu --no-pdf-header-footer --run-all-compositor-stages-before-draw --print-to-pdf=output.pdf index.html