Premium editorial blog header banner for an invoicing software brand. Wide landscape, clean off-white background, generous negative space, high-end SaaS marketing aesthetic. LEFT HALF: a bold left-aligned sans-serif headline reading exactly "Commercial vs Proforma", near-black, with the single word "Proforma" in a violet-to-indigo purple gradient — correct spelling, crisp kerning, no gibberish. Below it a smaller muted-gray subtitle reading exactly "Which invoice, and when". RIGHT HALF: two stacked semi-realistic 3D invoice documents fanned side by side, one tagged with a small "PROFORMA" ribbon and one stamped "FINAL", semi-realistic 3D render, soft realistic shadows, clean studio lighting. Thin minimal line-art accents, small violet accent dots. Palette: near-black, violet and indigo purple accents, light gray, off-white. Calm, modern, uncluttered. No watermarks, no busy icon soup, no logos.