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+# Scene prompt - Intro: the establishing shot (masthead backdrop)
+
+The one image the site opens on, behind the title. It is NOT a course scene: nothing gets sliced
+here, so the usual "generous void gaps between parts" rule relaxes. What it must do is read at a
+GLANCE as "a machine world seen from a distance", sit far enough back that white title text stays
+legible over it, and use the same materials as every course so the page feels like one object.
+
+Composition rule for this one: the CENTRE-TOP THIRD stays dark and quiet (the headline lives
+there). Weight the interest low and wide.
+Generate ~4 at 16:9, curate with the reject checklist, save to disk for pickup.
+
+---
+
+Dark technical exploded-view illustration in a cinematic sci-fi engineering style.
+Solid near-black deep void background, hex #070b14 - completely clean: no stars, no grid,
+no texture, no particles behind or around the objects. Matte dark metal-and-glass surfaces
+with glowing neon edge lighting: primary cyan #3fbaf5, secondary magenta #e879f9 accents,
+cool white rim highlights. Camera: fixed 30-degree isometric angle, even studio lighting, no
+vignette, no lens flare, no depth-of-field blur. ABSOLUTELY NO text, no letters, no numbers, no
+words, no code, no glyphs, no labels, no arrows, no callout lines, no UI elements anywhere in the
+image - every surface marking must be an abstract geometric pattern only.
+
+The subject: a wide establishing view of an entire machine world, seen from far away and slightly
+above, as if the whole facility has been taken apart and left floating in the dark. Across the
+lower two thirds of the frame, a loose archipelago of small dark machine forms drifts in the void
+with generous space between them: flat stacked slabs, a few chamfered cubes, a ringed cylinder, a
+faceted geodesic sphere lit from within, an open doorframe arch, a low armoured vault box, and
+several thin plates tumbling at angles. Each object is small in frame - none dominant - each
+picked out by fine cyan edge light with occasional magenta accents, and each fully surrounded by
+void. Scale falls away toward the horizon so the nearer objects are larger and the far ones are
+tiny points of cyan light. The upper third of the frame is almost entirely empty void, with only
+one or two faint distant shapes near the edges.
+
+---
+
+## Build-side notes (not part of the prompt)
+
+- **Usage:** masthead backdrop for the intro. NOT sliced - it renders as one image behind the
+  title block, scroll-parallaxed and faded out as the index arrives (motion class = parallax, so
+  it is disabled entirely under reduced-motion per house-motion-system).
+- **Curation gate specific to this image:** hold a light-grey rectangle over the centre-top third;
+  if the title would be hard to read there, reject the candidate. Busy-centre compositions fail
+  here even if they look great alone.
+- **Family check:** the objects should be recognisable relatives of the course heroes (slabs =
+  Course I, cubes = Course II workers, sphere = Course V core, arch = Routes, vault = the secret
+  store). A viewer who scrolls the whole site should feel they have just toured this picture.
+- **Processing:** WebP, 1600px wide, target <=180KB (it is a backdrop, quality can sit lower than
+  a scene hero since text overlays it and it is partly faded in use).
+- **Watermark:** Gemini sparkle bottom-right - strip with ffmpeg delogo before use.
+- **If it never gets generated:** the intro entrance already ships and works without art; this is
+  additive, not a blocker.