Add C to Rust Migration course landing page

[avollrath]

Summary

Adds a new landing page for the C to Rust Migration course at /c-to-rust-migration-book/.

TODO

• @marcoow to connect the Mailchimp audience to the subscription form
• @marcoow to add the links to the actual material and PDF
• @avollrath add og:image
• @avollrath replace HTML and PDF once Address TODOs in content migrating-c-to-rust#8 is fixed
• @marcoow finalize copy (look at my comments)

[marcoow]

This seems broken now?

[avollrath]

@marcoow

The slug in the PR description wasn't updated from the previous version (now it is), it should be /c-to-rust-migration/, so the working preview is here:

https://deploy-preview-2865--objective-northcutt-37494c.netlify.app/c-to-rust-migration/

I still need to address Linn's latest comments from Notion though.

[marcoow]

I think it looks good!

[marcoow]

"Your Mentor" makes sense for workshops but "Your author" sounds a bit strange

[marcoow]

I think the "by Mainmatter" needs to be closer to the headline (like it's here: https://rust-exercises.com) – otherwise it looks strange:

Should we have some kind of grid for these links so they don't look as unaligned?

I think it would be nice to have a larger image of Jonas (I know this is an existing component but still):

Is the arrow not on the wrong side?

I'll look into copy on Friday

[mainmatterlinnbp]

@marcoow I added the Mailchimp audience "Mainmatter C to Rust", so please use that for the sign-up form. I set it up as a duplicate based on the Rust audience, feel free to make any changes you see fit directly in Mailchimp.

[marcoow]

@avollrath @mainmatterlinnbp we should think about where and how this page is linked from the rest of mainmatter.com. If you get to this and navigate away, there should be a way to find it again?

[avollrath]

Screen.Recording.2026-06-30.at.15.58.48.mov

@marcoow If we want to keep it inline and with the same width, it comes with the tradeoff that that space needs to be reserved beforehand in the main menu -> so that's wider by default now. The caret icon ^ behaves the same as in the main menu (next to "More"), just flipping up and down.
I added subtle animation for the nested items appearing and the menu vertically expanding, so it feels a bit smoother.

What do you think about this version?

[marcoow]

I think this is better – stuff jumping around just isn't great. Should we not animate the caret as well?

[avollrath]

@marcoow

100%, no jumping is much better.

I've now done those adjustments:

• Added animations for the carets, nested menu items, and a quick overall menu opening animation (Had to use js for the nested menu animation because Safari does not reliably animate it smoothly with css only (animation is still just css transitions though))
• Reduced hero toc font size so it fits on a single line
• Added the books as a background for the mobile CTA block

I also made a those changes earlier:

• Increased Jonas' author image
• Switched the arrow position in the "Contact us" row
• Moved the "by Mainmatter" label closer to the title

I think that covers everything I was pinged for (Jonas updated html and pdf with the latest version today)

[marcoow]

All looks good to me. The 404s in the link crawler should be resolved once we open-source the GitHub repo. Please go ahead and merge this (after ensuring all checks pass) when ready.