Playful Decorative Alphabet Poster

Create a cheerful decorative alphabet poster featuring {argument name="letters" default="A through Z"} arranged in neat rows on a {argument name="background color" default="clean light background"}. Render the letters in a soft, bubbly display style with bold dark outlines and a charming mix of pastel tones. Give the alphabet a playful illustrated feel by pairing selected letters with small whimsical accents such as flowers, sparkles, hearts, bows, star shapes, and tiny graphic bursts. Scatter a few extra floral and decorative motifs between the rows to make the composition feel lively and well balanced. The overall aesthetic should feel inspired by {argument name="design era" default="retro 1970s"} print design, with a sunny, nostalgic, and cute visual mood, like a vintage stationery sheet or a playful classroom art poster.