Hi ​@Dammy — great question!

Currently in Miro, transparency/opacity controls are available for shapes, but not for lines or connectors. This means you can’t directly adjust the opacity of a line the way you can with a rectangle or circle.

If this is something you’d find useful, I’d recommend sharing your feedback via the Wish List — the product team keeps an eye on those posts.

Let me know if you’d like additional help!