Minimalist symbolic graphic poster

Generate a visual theme poster with a strong graphic sense around any subject: Let the subject content first be refined into a large single symbol or geometric main shape that occupies visual dominance; the main shape lifts slightly from the flat background like thick cardboard or flexible 3D sheets, with edges kept sharp and clean; an extremely thin high-brightness outline appears on one side, and a clear negative space hole or turning gap is left inside, making the first glance perceive huge physical pressure, and the second glance discover it is shaped by same-color layers, shadows, and edge highlights. The background uses an almost impurity-free full-surface theme base color; the main shape and background belong to the same theme color system, layered through differences in lightness, saturation, and shadow depth; colors are extracted from the material, emotion, and information attributes of the theme itself, retaining large areas of high-saturation or high-brightness emotional fields, deep structural shadows, a few clear bright edges, and small areas of information emphasis colors; the overall look should be bright, clean, direct, and ceremonial, avoiding grey/dirty, vintage/yellowed, or smoky treatments. The main shape casts a wide diagonal long shadow to one side, with edges that are soft yet hard, forming a strong sense of direction and presence tension. Text is embedded as information anchors in the whitespace pressure zones next to the main shape, using heavy, compact, and clear sans-serif characters; short sentences are arranged in lines, with font weight competing with the main shape but area restrained; a row of narrow, tall, and evenly spaced auxiliary English or slogans can be placed at the bottom to form a stable closure. Tiny handwritten-style symbols or annotations are allowed as slight contrasts, occupying only a very small area, like immediate marks left by a designer. The overall surface is smooth, the lighting is concentrated, and the boundaries are clean; the composition relies on the huge main shape, negative space holes, long shadows, and restrained text to establish memory points, rather than complex illustrations or decorative stacking.

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Change scene to: A same-color giant shadow countdown poster for the large number 7, continuing to retain the single numerical main shape and negative space hole.
Publishing scenario: A vertical social platform image for course opening or event warm-up.
Text retention: Chinese short phrase reads "开营倒计时", the bottom English slogan is short and restrained.
Dimensions: Landscape 16:9