Squircle app icon for a Question Bank application. A rounded-square base with a smooth blue-to-teal gradient, a subtle top-left highlight, and a delicate inner edge stroke. In the center, a bold white question mark creatively formed by minimalist book silhouettes: the curve of the question mark built from three slim, curved pages, and the dot as a tiny open-book glyph. Clean, flat design with a touch of bevel for subtle depth. Gentle drop shadow to lift the icon off a light background. High-contrast, highly legible at small sizes, suitable for a scalable vector icon. Transparent background for versatile use.

The image shows a black question mark icon on a white background, indicating that it is a representation of the question mark.