Help! My Shopify App Block Modal Position is Wrong

Hi everyone,
I’m making a Shopify app block using Vue 3 and TailwindCSS, but I’m stuck with a modal issue.

what happened:

  • The modal uses position: fixed and should open relative to the browser window (top-0, left-0).
  • Instead, it’s aligning to the product section, not the window.

Weird Part:

  • It works fine on a US-based VPS, but on my PC and other devices, it doesn’t work.
  • I’ve checked the HTML and CSS in the browser inspector, and they look the same.
  • I even tested in Chrome’s Guest Mode (no extensions, no cache), but the issue is still there.

How can I fix the modal so it always positions relative to the browser window on every device?
I’ve attached screenshots of the problem.

Thanks so much for your help!