Glass opacity 0% turns dark theme white; verify blur semantics

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Symptoms

1. Setting Glass opacity to 0% turns the dark-theme app into a white surface. Zero opacity should remove the glass film and make the surface transparent to what is behind it, not inject a light fallback.
2. Glass blur needs an outcome-level audit to prove it actually blurs backdrop content by the selected amount.

Required behavior

• 0% glass opacity produces transparent surface film while preserving dark/light theme context, foreground readability, borders, and intended backdrop composition.
• Opacity changes only the film contribution; it must not silently replace the base/backdrop with white.
• Blur acts on content behind the glass surface, not the panel foreground, and increasing the slider produces a measurable increase in backdrop smear.
• Disabling glass restores the authored solid surface without retaining blur/compositor resources.

Native verification

Use real Blitz paint/composition inspection in dark and light mode. Add focused ps-qa outcomes for 0%, an intermediate opacity, and restoration, plus a native rendered-effect check that distinguishes two blur levels against known behind-panel detail. Verify resolved colour/alpha and compositor/backdrop-filter state; do not use jsdom or a semantic slider-value change as proof that the visual effect works.

Screenshot

Owner supplied Screenshot 2026-08-29 at 02.57.30.png showing the white result at 0% in dark mode.