Feature 404 block design & features
The block is a mirrored variation of feature405, set in a running and training app. A soft colour panel holding a phone sits on the left, and the heading, paragraph and four feature rows sit on the right.
The rows have no icons. They hang off a thin vertical rule, and a darker line slides along that rule to mark the active row. Hovering, focusing or tapping a row makes it active, the panel crossfades to that row's flat colour, and the phone screen fades to a weekly training plan, a run with a route map and kilometre splits, a heart rate chart with time in zones, or a morning readiness score with sleep stages.
The phone and its screens are built in JSX with fixed light colours so they read the same in light and dark mode, and the bottom tab bar follows the active row. The heading, athlete name and capabilities, including each panel colour, are props. Rows are buttons with aria-pressed, and the slide and fade animations are switched off when the visitor prefers reduced motion.
On mobile the list sits above the phone panel and rows respond to taps.