fix: Fix C4 model font size on Firefox

[aristotelos]

Fix that font size was not applied in Firefox, resulting in badly rendered C4 model descriptions.

📑 Summary

Fix that numeric font size was not applied in Firefox. See how https://mermaid.js.org/syntax/c4.html is rendered in Firefox.

Fixes #7182.

📏 Design Decisions

Add "px" if font size is numeric.

📋 Tasks

Make sure you

• 📖 have read the contribution guidelines
• 💻 have added necessary unit/e2e tests.
• 📓 have added documentation. Make sure MERMAID_RELEASE_VERSION is used for all new features.
• 🦋 If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpm changeset and following the prompts. Changesets that add features should be minor and those that fix bugs should be patch. Please prefix changeset messages with feat:, fix:, or chore:.

[changeset-bot]

🦋 Changeset detected

Latest commit: 318bd12

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
mermaid	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[netlify]

✅ Deploy Preview for mermaid-js ready!

Name	Link
🔨 Latest commit	318bd12
🔍 Latest deploy log	https://app.netlify.com/projects/mermaid-js/deploys/692eb30b6368780008bd782c
😎 Deploy Preview	https://deploy-preview-7170--mermaid-js.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[pkg-pr-new]

Open in StackBlitz

@mermaid-js/examples

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/examples@7170

mermaid

npm i https://pkg.pr.new/mermaid-js/mermaid@7170

@mermaid-js/layout-elk

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/layout-elk@7170

@mermaid-js/layout-tidy-tree

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/layout-tidy-tree@7170

@mermaid-js/mermaid-zenuml

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/mermaid-zenuml@7170

@mermaid-js/parser

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/parser@7170

@mermaid-js/tiny

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/tiny@7170

commit: 318bd12

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 3.56%. Comparing base (ecf9ea1) to head (318bd12).
⚠️ Report is 47 commits behind head on develop.

Files with missing lines	Patch %	Lines
packages/mermaid/src/diagrams/c4/svgDraw.js	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #7170      +/-   ##
==========================================
+ Coverage     3.55%   3.56%   +0.01%     
==========================================
  Files          474     474              
  Lines        47508   47579      +71     
  Branches       731     734       +3     
==========================================
+ Hits          1687    1696       +9     
- Misses       45821   45883      +62     

Flag	Coverage Δ
unit	3.56% <0.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
packages/mermaid/src/diagrams/c4/svgDraw.js	0.00% <0.00%> (ø)

... and 3 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[argos-ci]

The latest updates on your projects. Learn more about Argos notifications ↗︎

Build	Status	Details	Updated (UTC)
default (Inspect)	✅ No changes detected	-	Dec 2, 2025, 9:46 AM