Highcharts Sankey Heatmap Infographic for Trend Progression

Data visualization infographic titled "Heatmap Example" using a SANKEY FLOW as the dominant visual element to show trend progression across stages over time. Create a large, center-weighted sankey / pipeline diagram with clear left-to-right flow and an overlaid subtle time progression guide beneath it, using sharp English axis labels and tick marks: horizontal guide labeled "Time" with ticks "Q1", "Q2", "Q3", "Q4"; vertical reference label "Flow volume (illustrative units)". Structure the sankey as four sequential periods with plausible illustrative values: from "Initial signals" 420 in Q1 splitting to "Low intensity" 180, "Medium intensity" 150, "High intensity" 90; Q2 aggregated transitions 460 total; Q3 520 total; Q4 610 total, with visibly thicker flows ending in stronger concentration toward higher-intensity nodes by Q4: "Low intensity" 170, "Medium intensity" 210, "High intensity" 230. Add compact side heatmap-style color chips or node fills to reinforce intensity levels from light warm beige to deep rust, while keeping the sankey as the main chart. Ensure all labels, legends, metric names, node names, captions, and annotations are in English only and crisply legible.

Include 4 key insight callouts placed around the chart, each with a headline number, short interpretation in English, and a small icon: 1) "610" + "Total flow peaks in Q4, up from 420 in Q1" + upward trend icon. 2) "230" + "High-intensity segment becomes the largest growth driver by year-end" + flame or hotspot icon. 3) "45%" + "Share ending in medium or high intensity expands markedly over the period" + stacked layers icon. 4) "170" + "Low-intensity flow stays comparatively stable while stronger categories gain" + balance icon.

Add a compact legend in English: "Intensity scale" with labels "Low", "Medium", "High". Add a small source / data-note strip at the bottom in English reading: "Data note: Illustrative example. Figures are illustrative and not sourced from an external dataset." Include a small note near values saying "illustrative" where appropriate. Explicitly avoid misleading axis truncation or manipulated scales.

Visual style: NYT graphics desk, Economist warm beige palette, understated editorial typography, muted cream background, warm beige, sand, terracotta, rust, charcoal accents, subtle gridlines, elegant spacing, restrained annotation system, editorial data journalism illustration, FT / Bloomberg-grade chart aesthetics, vector-clean infographic layout. Overall mood: analytical, trustworthy, refined, print-magazine quality, high clarity, modern newsroom explainer.

All text MUST be written in English (array). Every heading, label, caption, legend and metric name in the image must be in English — not English. Spell each English word correctly using English characters and diacritics. Numbers stay as digits, no fake authoritative sources cited, no watermarks Numbers labeled "illustrative" unless the user supplied specific sourced data. No fake authoritative sources cited (do not invent "Source: Reuters 2025" — use "Illustrative example" instead). No misleading axis truncation or scale manipulation.