bug: Start/End node styles reference unavailable Tailwind CSS variables inside Shadow DOM

[fantonangeli]

Describe the Bug

Some Start/End node styles reference CSS variables that are not available when the Diagram Editor is embedded inside a Shadow DOM host using Web Components.

Observed examples include missing Tailwind internal variables such as --tw-border-style.

Steps to reproduce

1. Build @serverlessworkflow/diagram-editor.
2. Embed the Diagram Editor in a Shadow DOM host application.
3. Load the generated dist/styles.css inside the shadow root.
4. Render a workflow containing Start/End nodes.
5. Notice that the Start/End nodes are missing the expected border styling.

Expected Behavior

Start/End nodes should render with the expected border and styles without relying on undefined CSS variables.

Editor Version

0.1.0

Platform

Web / Browser

Additional Context

This was noticed while embedding the Diagram Editor in Quarkus Dev UI, which uses Lit/Web Components and Shadow DOM.