Transit chord network

<!-- Original layout, SVG/CSS artwork and JavaScript © 2026 XXC Templates. MIT License.
Illustrative sample content and data; no real accounts, purchases or bookings. -->
<main>
  <header class="intro">
    <div>
      <div class="kicker">DATA STORIES / SAMPLE DATA</div>
      <h1>Transit chord network</h1>
      <p>
        A circular network connects six city districts. Link widths encode trips; select a district
        to isolate its connections.
      </p>
    </div>
    <span class="badge">INTERACTIVE SVG</span>
  </header>
  <section class="panel">
    <div class="chord-layout">
      <svg
        id="chart"
        viewBox="0 0 700 315"
        role="img"
        aria-label="Weighted circular transit network"
      ></svg>
      <div>
        <p class="kicker">SIX DISTRICTS</p>
        <div id="districts" class="toolbar"></div>
        <p>Thicker routes carry more daily trips.</p>
        <button id="change">Cycle focus district</button>
      </div>
    </div>
    <output id="status" class="status" aria-live="polite"></output>
    <details class="data-table">
      <summary>View data table</summary>
      <div class="table-scroll"><table id="data-table"></table></div>
    </details>
  </section>
  <footer>Illustrative data · no external services · keyboard-accessible controls</footer>
</main>

:root {
  --bg: #071c2a;
  --panel: #0c293b;
  --text: #e3f9fc;
  --muted: #92b8c8;
  --line: #245065;
  --accent: #64dfd7;
}
/* Original XXC Templates Studio collection. MIT; sample data only. */
* {
  box-sizing: border-box;
}
html {
  color-scheme: dark;
}
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font:
    14px/1.6 system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  padding: clamp(18px, 4vw, 40px);
  min-height: 100vh;
}
h1,
h2,
h3,
p {
  margin: 0;
}
h1 {
  font-size: clamp(27px, 4.8vw, 46px);
  line-height: 1.07;
  letter-spacing: -0.055em;
  font-weight: 650;
}
h2 {
  font-size: 22px;
  letter-spacing: -0.025em;
  line-height: 1.2;
}
h3 {
  font-size: 15px;
}
p {
  color: var(--muted);
}
button,
input,
select {
  font: inherit;
}
button,
a,
input,
select,
summary {
  touch-action: manipulation;
}
button {
  cursor: pointer;
  color: var(--text);
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 9px;
  padding: 9px 14px;
  font-size: 12px;
}
button:hover {
  border-color: var(--accent);
}
button[aria-pressed="true"],
button.active {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
}
button:disabled {
  opacity: 0.5;
  cursor: default;
}
button:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible,
summary:focus-visible,
[tabindex]:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 4px;
}
a {
  color: inherit;
  text-underline-offset: 4px;
}
input,
select {
  min-width: 0;
  max-width: 100%;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 9px;
}
input[type="range"] {
  accent-color: var(--accent);
  padding: 0;
}
input[type="checkbox"] {
  accent-color: var(--accent);
}
label {
  display: flex;
  gap: 8px;
  align-items: center;
  font-size: 12px;
  color: var(--muted);
}
svg {
  max-width: 100%;
  display: block;
}
img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}
main {
  max-width: 1120px;
  margin: auto;
  min-width: 0;
}
.kicker {
  text-transform: uppercase;
  letter-spacing: 0.17em;
  font:
    10px/1.6 ui-monospace,
    monospace;
  color: var(--accent);
}
.intro {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  align-items: center;
  margin-bottom: 25px;
}
.intro h1 {
  margin: 8px 0 10px;
}
.intro p {
  max-width: 470px;
  font-size: 13px;
}
.badge {
  display: inline-flex;
  border: 1px solid var(--line);
  border-radius: 50px;
  padding: 5px 10px;
  font:
    10px ui-monospace,
    monospace;
  color: var(--muted);
}
.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 22px;
  min-width: 0;
}
.toolbar {
  display: flex;
  gap: 9px;
  flex-wrap: wrap;
  align-items: center;
  margin: 16px 0;
}
.primary {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
}
.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 15px;
}
.muted {
  color: var(--muted);
}
.metric {
  font-size: 36px;
  letter-spacing: -0.05em;
  font-weight: 600;
}
.mono {
  font-family: ui-monospace, monospace;
}
.rule {
  border: 0;
  border-top: 1px solid var(--line);
  margin: 20px 0;
}
footer,
.footnote {
  font-size: 10px;
  color: var(--muted);
  margin-top: 18px;
}
.status {
  display: block;
  min-height: 20px;
  margin-top: 10px;
  color: var(--accent);
  font-size: 12px;
}
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
}
[hidden] {
  display: none !important;
}
.data-table {
  margin-top: 16px;
  font-size: 11px;
  color: var(--muted);
}
.data-table summary {
  cursor: pointer;
}
.table-scroll {
  overflow: auto;
  max-width: 100%;
}
table {
  border-collapse: collapse;
  width: 100%;
  font-size: 11px;
}
th,
td {
  text-align: left;
  border-bottom: 1px solid var(--line);
  padding: 9px;
  white-space: nowrap;
}
caption {
  text-align: left;
  color: var(--muted);
  padding: 8px 0;
}
.legend {
  display: flex;
  gap: 17px;
  flex-wrap: wrap;
  font-size: 11px;
  color: var(--muted);
}
.legend i {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--c);
  margin-right: 6px;
}
dialog {
  max-width: calc(100vw - 36px);
  width: 460px;
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 25px;
}
dialog::backdrop {
  background: #000a;
}
dialog p {
  margin: 12px 0;
}
.media-credit {
  font-size: 9px;
  margin-top: 16px;
  color: var(--muted);
}
.stage {
  position: relative;
  min-height: 290px;
  border-radius: 18px;
  overflow: hidden;
  border: 1px solid var(--line);
  background: var(--panel);
}
@media (max-width: 520px) {
  .intro {
    align-items: flex-start;
    flex-direction: column;
  }
  .grid {
    grid-template-columns: 1fr;
  }
  .panel {
    padding: 17px;
  }
  .toolbar label {
    flex-wrap: wrap;
  }
  .stage {
    min-height: 270px;
  }
  h1 {
    font-size: 32px;
  }
  .intro p {
    font-size: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  *,
  *:before,
  *:after {
    animation: none !important;
    transition: none !important;
    scroll-behavior: auto !important;
  }
}
html {
  color-scheme: dark;
}
#chart {
  width: 100%;
  height: auto;
  overflow: visible;
}
#chart text {
  font-family: system-ui, sans-serif;
  fill: var(--muted);
  font-size: 11px;
}
.chart-summary {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 15px;
}
.chart-summary strong {
  font-size: 33px;
  letter-spacing: -1.4px;
}
.chart-summary span {
  font-size: 11px;
  color: var(--muted);
}
.chord-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) 1fr;
  align-items: center;
  gap: 15px;
}
.chord-layout #chart {
  max-height: 315px;
}
@media (max-width: 520px) {
  .chord-layout {
    grid-template-columns: 1fr;
  }
}

(() => {
  "use strict";
  const $ = (s) => document.querySelector(s),
    $$ = (s) => [...document.querySelectorAll(s)],
    status = (t) => {
      const el = $("#status");
      if (el) el.textContent = t;
    },
    clamp = (n, a, b) => Math.max(a, Math.min(b, n));
  const reduced = matchMedia("(prefers-reduced-motion: reduce)").matches;
  const ns = "http://www.w3.org/2000/svg";
  function svg(tag, attrs = {}, text) {
    const el = document.createElementNS(ns, tag);
    for (const [k, v] of Object.entries(attrs)) el.setAttribute(k, String(v));
    if (text !== undefined) el.textContent = text;
    return el;
  }
  function table(headers, rows) {
    const t = $("#data-table");
    if (!t) return;
    t.replaceChildren();
    const caption = document.createElement("caption");
    caption.textContent = "Illustrative sample data";
    t.append(caption);
    const head = t.createTHead().insertRow();
    headers.forEach((v) => {
      const th = document.createElement("th");
      th.scope = "col";
      th.textContent = v;
      head.append(th);
    });
    const body = t.createTBody();
    rows.forEach((row) => {
      const r = body.insertRow();
      row.forEach((v) => (r.insertCell().textContent = String(v)));
    });
  }
  function selectButtons(selector, callback) {
    $$(selector).forEach((b) =>
      b.addEventListener("click", () => {
        $$(selector).forEach((x) => x.setAttribute("aria-pressed", String(x === b)));
        callback(b);
      }),
    );
  }

  const colors = ["#82b6ff", "#72dbc2", "#c5a4ff", "#f7bf7c", "#fa92b8", "#acd884"];
  const names = ["North", "Harbor", "Old town", "Gardens", "Market", "West"],
    links = [
      [0, 1, 42],
      [0, 2, 28],
      [0, 4, 18],
      [1, 3, 35],
      [1, 5, 25],
      [2, 3, 48],
      [2, 4, 30],
      [3, 5, 20],
      [4, 5, 44],
    ];
  let focus = -1;
  function draw() {
    const s = $("#chart");
    s.replaceChildren();
    const pt = (i) => ({
      x: 350 + Math.cos((i * Math.PI) / 3 - Math.PI / 2) * 127,
      y: 158 + Math.sin((i * Math.PI) / 3 - Math.PI / 2) * 127,
    });
    links.forEach(([a, b, n]) => {
      const p = pt(a),
        q = pt(b);
      s.append(
        svg("path", {
          d: "M" + p.x + " " + p.y + "Q350 158 " + q.x + " " + q.y,
          fill: "none",
          stroke: colors[a],
          "stroke-width": n / 5,
          "stroke-opacity": focus < 0 || a === focus || b === focus ? 0.65 : 0.08,
        }),
      );
    });
    names.forEach((name, i) => {
      const p = pt(i);
      s.append(svg("circle", { cx: p.x, cy: p.y, r: 10, fill: colors[i] }));
      s.append(
        svg(
          "text",
          {
            x: p.x + (p.x < 350 ? -16 : 16),
            y: p.y + 4,
            "text-anchor": p.x < 350 ? "end" : "start",
          },
          name,
        ),
      );
    });
    $$("#districts button").forEach((b, i) => b.setAttribute("aria-pressed", String(i === focus)));
    table(
      ["From", "To", "Trips"],
      links
        .filter(([a, b]) => focus < 0 || a === focus || b === focus)
        .map(([a, b, v]) => [names[a], names[b], v]),
    );
  }
  names.forEach((name, i) => {
    const b = document.createElement("button");
    b.textContent = name;
    b.addEventListener("click", () => {
      focus = i;
      draw();
      status("Showing routes connected to " + name + ".");
    });
    $("#districts").append(b);
  });
  $("#change").addEventListener("click", () => {
    focus = (focus + 1) % 6;
    draw();
    status("Showing routes connected to " + names[focus] + ".");
  });
  draw();
})();