fix: inactive overlay z-index broken by JS-style comment in CSS

[j4rviscmd]

Problem

The inactive window overlay (added in #213) was invisible in production builds. When the window lost focus, the overlay element was created and coderm-inactive-overlay-visible was applied, but it stayed hidden behind the workbench.

Root Cause

The overlay CSS is injected via a template literal. The z-index: 10000 declaration was preceded by JS-style // Why: comments:

.coderm-inactive-overlay {
    ...
    // Why: 10000 deliberately sits above every standard VS Code layer
    // (modal editor backdrop=2540, ...)
    z-index: 10000;
}

CSS only recognizes /* */ comments. The parser treated // as an invalid token and discarded the entire declaration up to the next ; — which was the z-index: 10000; terminator. As a result z-index fell back to auto (≈0), and since .monaco-workbench has z-index: 1, the overlay rendered behind the workbench and was never visible.

This only surfaced in production: the dev build's simpler stacking context let z-index: auto still appear on top, but the full production workbench creates a z-index: 1 stacking context that hid the overlay.

Fix

Convert the // Why: lines to CSS-valid /* Why: ... */ so the parser no longer discards z-index: 10000.

Verification

• DevTools (CDP): z-index computed value went from auto → 10000 after the fix
• Overlay now renders above the workbench when the window loses focus (confirmed in dev build)

🤖 Generated with Claude Code