Describe the bug
The sticky action button, which should remain fixed as users scroll through the page, is no longer functioning as intended. Instead, the button scrolls out of view with the rest of the page, impacting usability and making it harder for users to perform actions quickly.

To Reproduce
Steps to reproduce the behavior:

1. Navigate to a page with a sticky action button (e.g., a proposal with active votes): https://nightly.decidim.org/processes/thank-turkey/f/7/proposals/4
2. Scroll down the page.
3. Observe that the action button no longer stays fixed and scrolls out of view.

Expected behavior
The action button should remain visible (sticky) as users scroll through the page, allowing easy access to perform actions at any time.

Additional context
This was implemented via #13002.

Extra data

• Device: Desktop
• OS: Ubuntu 22.04
• Browser: Chrome
• Decidim Version: 0.30.0.dev
• Installation: Nightly