Generate AI Illustration: Yoga Event Flyer with Watercolor Style

"Goal: Create a square illustrated Japanese event flyer for {argument name="event title" default="ヨガとドリンクの夕べ"}, promoting an outdoor yoga-and-drinks evening for desk workers. Canvas: 1:1 square flyer, soft watercolor illustration, calm natural palette, hand-painted texture, gentle ink outlines, inviting wellness-event atmosphere. Layout: Use three horizontal zones: a translucent pale green title banner across the top, a large central garden illustration, and a cream information panel along the bottom. Keep all typography bold, clean, white or dark charcoal, with subtle drop shadows on the headline for readability. Top text: Large Japanese headline: {argument name="event title" default="ヨガとドリンクの夕べ"}. Beneath it, smaller Japanese subtitle: {argument name="subtitle text" default="デスクワークの疲れをヨガで癒す"}. Central illustration: A peaceful Japanese-style park beside a pond, with leafy trees, shrubs, stepping-stone path, a stone lantern on the right, a simple wooden bench, rocks, grass, and a few scattered red leaves. Show exactly 3 yoga participants on mats: 1 seated woman in the foreground wearing a teal ribbed long-sleeve top and dark pants, sitting cross-legged with relaxed hands on knees; 1 woman on the left wearing a white sleeveless top and loose white pants, seated cross-legged and stretching one arm behind her head; 1 man in the rear wearing a light gray T-shirt and navy shorts, barefoot on a mat, bending forward with hands near knees. Add exactly 1 wooden drink tray on the grass to the right of the foreground mat, containing exactly 3 drink items: 2 stemmed glasses filled with amber/orange drinks and 1 tall bottle with a warm-colored label. Bottom information panel: Cream rectangle with three bold Japanese lines, aligned left: {argument name="date and time" default="日付・時間: 6/20（土）15:00-20:00"}, {argument name="location" default="場所: 新宿御苑"}, and {argument name="organizer" default="主催: 小規模IT事業者連盟"}. Constraints: Preserve the Japanese text exactly as written in the parameter defaults, make the flyer look like a finished event poster rather than a photo, avoid logos or watermarks, keep the faces simple and unobtrusive, and do not add extra people, extra drinks, or extra text."