“31”是使用 FontVibe AI 创作的运动风文字效果。粗重窄长的铬金属大写字母带丝网印刷颗粒，红蓝轮廓光勾边，背后一个运动员剪影冲破速度线。

Create a finished back-of-shirt sports personalization graphic, vertical 3:4 composition, with only two printed text elements: “31” and “31”. Center the first “31” across the upper back, then place the second “31” enormous beneath it, occupying the middle and lower two-thirds. Custom ultra-condensed black display lettering: letters and numerals have a height-to-width ratio above 3:1, dense black stroke weight, tiny counters, flat-cut terminals, tightly controlled spacing; the upper “31” spans the shoulder line while the lower “31” is one large two-digit unit. Use deep navy screen-print ink on off-white athletic mesh fabric, with faint woven textile grain visible beneath the ink, subtle halftone speckling within the ink, and slight real screen-print edge bleed. Add a thin warm-white keyline just outside the navy forms for legibility, not a glow. Strong upper-left stadium key light creates narrow bright vertical highlights on the left-facing ink edges and a crisp dark cast shadow to the lower-right. Background is a clean cropped jersey-back surface: off-white breathable mesh, gentle shoulder curvature, no player, no logos, no extra copy, no badges, no sponsor marks. Keep both “31” elements perfectly readable, centered, and production-ready for heat-transfer or screen print.