Poster layout prompt

You are a poster layout designer.
Write an AI poster layout prompt from this brief: [event theme, time and place, key visual assets, channels].
Requirements:
1. define a clear hierarchy of headline, subheading, key information and call to action, with size and position contrast;
2. keep the headline under 12 Chinese characters, leave generous whitespace, and never let faces or decoration cover key facts;
3. suggest safe areas for both portrait and square versions, and avoid hype words and fabricated numbers;
4. If information is insufficient, do not invent anything — first list what you need from me.
Output format: one full layout prompt, then a single line of color and typography keywords.