Insight card

// Copyright (c) 2026 Bruno Delorence. MIT License.'use client';import { useEffect, useId, useRef, useState, type CSSProperties, type PointerEvent } from 'react';import { Backdrop, FolderDrawing, GLYPHS, SCANNER, funnelPolygon } from './drawings';import styles from './insight-card.module.css';/* * Insight card: a feature card whose picture shows raw data turned into insights. Round badges of * sources stream in from the left through a funnel of light, into a glowing scanner; folders of * findings slide out of it on the right. * * - Every size is a multiple of one unit, the card's width over 538, so the picture keeps its *   proportions at any width. The funnel, its glow and the blue beyond are one static SVG. * - Three rows move, each a row of fixed drawings shifted by its transform with the Web *   Animations API: the sources glide on steadily, one a second; the dotted particles in the *   funnel drift with them; the folders step on by one, eased, every third source. Each row holds *   two rounds of its drawings and loops by exactly one round, so the loop has no seam. * - The scanner hides what passes it: the sources' row is clipped at its line, and the folders' *   row is clipped there too; a band of frost just past the line whitens them as they come out. * - It plays only while on screen in a visible tab. Hovering the card slows it to a third, the *   speed eased in and out. A button pauses it; under reduced motion it starts still, as a frame. * - Light or dark: the stage, the card and its words are light-dark() tokens in the stylesheet, so

/* Insight card (insight-card.tsx): a card on a stage of its own, its picture above its title.   Every size is a multiple of --u, the card's width over 538, so the card scales as one drawing;   the stage is a size container and the card's width follows it, up to 540px. The scene is one   layout boundary of a size computed from that width, so nothing inside it lays out the page.   Motion. Three rows move by their transform alone, each on a layer of its own: the sources, the   particles and the folders. Their clips and the mask that fades the folders in are fixed boxes   around them; the scanner and its glows are fixed gradients over them.   Colours. The interface's are the tokens below, each light-dark(light, dark): the card takes the   color-scheme it inherits from the page (light unless the page says otherwise), or the one its   colorScheme prop sets (data-color-scheme). The picture (drawings.tsx, and the haze, particles,   badges, frost and scanner here) is content: the same in both. --text and the rows' places, set   on the scene and the picture, are sizes, so no token below takes those names. */.stage {  /* The stage, and the card on it: white on white by day, the card a step lighter at night. */  --surface: #fff;  --surface-2: #fff;  /* The title, the line under it, and the stage's own text. */  --ink: #383838;  --ink-muted: #6b6b6b;  --ink-soft: #484848;

/* * The insight card's drawings: the backdrop of its picture (the funnel on the left, the light * streaks on the right), the glyphs of the sources that flow in, and the folders that come out. * Every drawing is static; the card moves the boxes that hold them. *//** The picture's box, in the units every size of the card is a multiple of. */export const MEDIA = { width: 512, height: 277 };/** Where the scanner stands, across the picture. */export const SCANNER = 223;/** The funnel's upper and lower edges, from the left side to the scanner. */export const FUNNEL_TOP = 'M0 0C70 50 130 95 223 105';export const FUNNEL_BOTTOM = 'M0 277C60 240 120 195 223 191';/** A point of a cubic Bézier curve. */const bezier = (t: number, a: number, b: number, c: number, d: number) =>  (1 - t) ** 3 * a + 3 * (1 - t) ** 2 * t * b + 3 * (1 - t) * t ** 2 * c + t ** 3 * d;/** * The inside of the funnel, kept `inset` units clear of its edges (a negative inset reaches past * them), as a CSS polygon in shares of the left part of the picture (the scanner's width by the * picture's height). */