Compose a minimalist information poster with a ceremonial feel around any theme. At first glance there must be a precisely centered main title within a vast empty field of warm white, in solemn counterpoint to three thematic symbols: the theme supplies the core name, participants, or keywords, converted into a large thin-stroke title at the top, a recognizable set of abstract marks at center, and solid-color blocks on both sides — the semantics vary but the order stays fixed. Keep a high proportion of white space, a vertical central axis, top/bottom zoning, and the pause rhythm of thin black horizontal lines; arrange all elements with restraint, like an exhibition catalog or an international institution's yearbook. The main text uses a high-contrast thin serif or equivalent letterform with open counters, slender strokes, sharp clean terminals, and airy rhythm, keeping a slender skeleton, loose tracking, clear legibility, and calm breathing in any writing system, rather than copying a specific Latin typeface. Colors extract two high-purity representative hues from the theme as hard-edged blocks; the central mark uses only black lines and a little solid geometry; the background is a slightly paper-textured warm white, avoiding gradients, shadows, and decorative textures. At the bottom, with a lower center of gravity, place the subtitle and small explanatory text; in the footer, three-point micro-information anchors the edge, forming the contrast of a grand theme tamed by museum-like white space. Failure symptoms: elements become crowded, colors turn gaudy, fonts grow thick, icons become realistic, or the poster loses its austere ceremonial order. —————— Set the theme as "City Public Library Open Day," for the main poster of a public cultural institution's event: use indigo and cinnabar red as the two high-purity block colors, with black lines at center abstracting open book pages and a gateway arch; the symbol group descends steadily beneath the title along the vertical axis; the main title sits centered in the upper half, with subtitle and date forming a sparse two-tier information hierarchy below; keep large areas of warm white space and thin black line pauses; vertical format 3:4.