TITLE: Alpine Sunrise — Five Ridges, 4 810 Metres

PROMPT: Build a single self-contained HTML page that is a scroll-driven alpine sunrise. A 340vh scroll track contains a 100dvh position:sticky scene with overflow hidden, so the landscape stays pinned while scroll climbs. Palette: pre-dawn #0b1026, ridge #2b3a67, mid #6b8fb5, alpenglow #f2b880, sun #ffe9c9. Sky is three stacked full-bleed linear-gradient layers (night #04060f→#0b1026→#1e2749, dawn #101a3d→#2b3a67→#5d7fa8→#f2b880→#ffe9c9, day #123156→#3a6d9e→#8fb9d8→#e2d4bb) crossfaded by scroll progress, plus a horizon radial glow that blooms at dawn. A star field of 84 deterministic pseudo-random dots (seeded mulberry32) sits in the top 62%, one in three twinkling with a transform+opacity keyframe. The sun is a radial-gradient disc with two large warm box-shadow glows and a halo layer; its position is driven by a polar arc: angle a = PI*(1-p*0.5), x = 50-36cos(a) vw, y = 46-40sin(a) vh, so it starts just above the right-hand ridge line and climbs to the zenith as you scroll, scaling 0.82→1.14. Five hand-authored clip-path polygon ridges (16-18 points each, darkening from #4a5c88 far to #080d1c near) get individual translateY parallax (26/38/52/68/92px) and a 3-8% scale-up, each carrying a warm alpenglow gradient child whose opacity is scroll-driven. Three fog bands are soft radial gradients (no blur filter) drifting on 46s/63s/81s alternate CSS animations with negative delays, plus scroll-driven vertical offset. Six inline SVG gull silhouettes cross the top with staggered infinite translate3d animations, visible only around dawn. A fixed HUD top-left shows an oversized tabular-numeral elevation readout counting 0→4 810 m, a phase label, a grade percentage, and a vertical 5-tick scale whose fill scales and whose dot marker translates up as you climb. A summit pin sits on the far ridge peak with a hairline stem; hovering it reveals a Georgia italic quote card that slides up and fades in. Bottom-left title block: ui-monospace eyebrow, then "ALPINE / SUNRISE" in system-ui 200 uppercase with .34em letter-spacing, the second word in sun-cream. Bottom-centre scroll hint with an animated hairline. A vignette and a 3px repeating-linear-gradient grain sit on top. Pointer movement tilts four depth groups (sky/far/mid/near) by 5/11/18/27px with rAF lerp. Clicking anywhere (or the Night button, or pressing N) toggles night mode: sky holds pre-dawn, stars stay full, ridges lose all warmth, and the sun becomes a pale blue moon. All of this obeys prefers-reduced-motion.

DESCRIPTION: A cinematic five-layer alpine landscape that behaves like a slow ascent. The page opens in pre-dawn dark with a cold star field and the sun barely clearing the ridge line; as the visitor scrolls, the sky crossfades through dawn into day, alpenglow creeps up every ridge, fog drifts between the layers, gulls cross the sky, and the elevation HUD counts up to the summit. The scene is pinned so the scroll feels like climbing rather than scrolling, and the pointer adds a gentle depth tilt so the ridges separate like a stereoscope.

TECHNIQUES: position:sticky full-viewport stage inside a 340vh track; three-layer sky crossfade via scroll-driven opacity; polar-coordinate sun arc; hand-authored multi-point clip-path ridge silhouettes; per-ridge translateY+scale parallax; scroll-driven custom opacity on alpenglow gradient children; blur-free soft radial fog with alternate CSS drift animations; deterministic seeded star field with twinkle keyframes; inline SVG gulls with staggered infinite translate3d; rAF scroll lerp with a dirty gate (idle = zero writes); rAF-lerped pointer tilt on four depth groups; tabular-numeral elevation counter; hover-revealed serif quote card; body-class night mode; prefers-reduced-motion media query plus a matchMedia flag.

INTERACTION: Scroll to climb — the sun arcs from the right horizon to the zenith, the sky crossfades pre-dawn to dawn to day, alpenglow rises up all five ridges, fog bands drift and slide, gulls cross during first light, and the HUD counts elevation from 0 to 4 810 m while the grade percentage eases down. Move the pointer to tilt the four depth groups against each other. Hover (or focus) the summit pin to reveal the italic quote card and brighten the pin glow. Click anywhere on the scene, press the Night button, or hit the N key to toggle night mode — stars stay lit, the sun becomes a pale moon, all ridge warmth is removed, and the phase readout switches to night watch. Resizing re-measures the track, the HUD scale and the elevation mapping.