Default mono-space font is not mono-space

[S0AndS0]

Describe the bug

Default mono-space font is not mono-space, especially noticeable when using non-ASCII characters

To Reproduce
Steps to reproduce the behavior:

1. Write a /tmp/test.md file with the following content

┏━━━━━━━━━━━━━━━┓
┃     If you have to ask the price    ┃
┃         then you cannot afford       ┃
┃                   Special Hugs                ┃
┗━━━━━━━━━━━━━━━┛

2. Use freeze /tmp/test.md
3. Preview with okular freeze.png
4. Notice how things almost line-up, but don't

Expected behavior
I expect something like the following input to be mono-spaced, in Vim (I use Vim BTW™), and on GitHub;

┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃   If you have to ask the price    ┃
┃      then you cannot afford       ┃
┃          Special Hugs             ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛

... but it seems even The GitHubs no likes to mono-space 0x2501 characters :-\

Screenshots

If applicable, add screenshots to help explain your problem.

Example of Freeze output given first given input

Example of Vim display with second example input

Desktop (please complete the following information):

• OS: GNU Linux (Arch BTW™)
• Browser "Wat?!"
• Version freeze version v0.2.2 (80921ba)

Smartphone (please complete the following information):
Not Applicable

Additional context
Not Applicable

---

Update -- 2025-05-24

Found a work-around!

• Find mono-space fonts available on system

  fc-list | sort -u | grep -i mono

• Mess about to find something that really is mono-space by defining it in configs
  ~/.config/freeze/user.json (snip)

  {
  	"font": {
  		"family": "Liberation Mono",
  		"file": "/usr/share/fonts/liberation/LiberationMono-Regular.ttf",
  		"size": 14,
  		"ligatures": false
  	}
  }

• Explicitly use config

  freeze -c ~/.config/freeze/user.json -l markdown <<'EOF'
  ```
  ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
  ┃   If you have to ask the price    ┃
  ┃      then you cannot afford       ┃
  ┃          Special Hugs             ┃
  ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
  ```
  EOF

• Delight in the joy of mono-space font that is mono-space

While this doesn't resolve the issue of freeze default mono-space font not being mono-space, nor will it work on systems without alternative fonts to chose from, but hopefully this Issue will help anyone else struggling with making questionable usage choices x-)

[rahji]

FYI The workaround does not work for me. I get:

ERROR  Unable to write output
width and height are positive and non-zero

This seems like a pretty big bug (not being able to produce valid output - and the cryptic error from the workaround)

PS I was able to get it to work by specifying a font family on the command line: freeze --font.family "Noto Mono" --execute "ls" (easier than making a config file)