Glass presets: what the blur actually costs

Glass is the preset people try first and the one they most often switch away from. That is not a bug report — it is the effect doing exactly what it says, on pages that were never designed for it.

What the preset does

A glass preset inserts a translucent layer and asks the compositor to blur whatever is behind it. Two consequences follow immediately:

1. The page's own background stops being visible at full contrast, so text sits on a moving colour field rather than a flat one.
2. The browser has to re-blur on every scroll frame, not just on paint.

The second point is why glass feels different from every other preset. Warmth and dark themes are colour maths on existing pixels; they cost the same whether you scroll or sit still.

The three cases where it earns the cost

• Documentation and dashboards with large empty margins. The blur has room to work and the text column is narrow enough that contrast never becomes a question.
• Pages with a photographic hero you want to keep visible. A flat tint kills the image; glass keeps it legible underneath.
• Screenshots for presentations. This is the honest one — glass photographs well.

When to pick something else

• Dense code and log views. Monospace text on a blurred background is measurably slower to read, because the glyph boundaries lose contrast at the edges.
• Low-end hardware and battery-sensitive laptops. If you notice the scroll stutter, you are paying for it in battery too. Use a warm tint at the same intensity instead.
• Video players and canvas apps. The blur layer competes with the page's own compositing.

Intensity behaves differently here

On other presets the intensity slider mostly controls alpha. On glass it controls both alpha and blur radius, and the relationship is not linear. Below 40% you get a flat translucent panel with almost no blur — which is a perfectly good effect and much cheaper. Above 70% the blur radius stops adding visible difference but keeps adding frame cost.

Our recommendation for daily use is 45–60%. That range is where the panel reads as glass without the radius becoming decorative.

Does it work with dark themes

Yes, and it is one of the better combinations: a glass panel over a dark page keeps the background readable while removing the flatness that makes dark mode look like a terminal.

Frosted glass is part of the vivid set, which is Pro only — there is no trial. On Free you get the 11 eyecare, high-contrast and dark presets; the pricing page has the full breakdown, and the preset gallery shows every glass preset at its real settings.