Couple's route: a flight line with a plane and stops

One file, zero dependencies, “use client” for the progress and pins. The line is an SVG viewBox 1000×260 with a path of T-segments: the segment ends are exactly the stop points, so pins sit on the curve. The plane is a path with offset-path:path(...) and offset-distance from --vibeui-about-012-p; the covered part is a second path with pathLength=1 and stroke-dashoffset from --vibeui-about-012-k. Both variables are written by an rAF scroll handler from the section's position in the window (0 entering from below, 1 once the centre has passed), without re-renders. Pins are <g role=button tabIndex> with data-active, [data-part=stop] cards highlight with a border and lift. The card grid is 4 per row from 56rem. Exactly four stops: extras are dropped. Palette --vibeui-about-012-* is neutral: ink and paper via light-dark(), the site colours come through the accent, ink and background props; dark theme via .dark/[data-theme] or tone. Oswald, Lobster and Manrope come via <link precedence> from Google Fonts with system fallbacks. accent and background override colours, prefers-reduced-motion disables animations.