Request sequence studio

<!-- 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">CONNECTED THINKING / DIAGRAMS</div>
      <h1>Request sequence studio</h1>
      <p>
        A step-by-step sequence diagram with lifelines, request arrows and explanatory captions.
        Move through a complete local sign-in illustration.
      </p>
    </div>
  </header>
  <section class="panel">
    <svg
      id="chart"
      viewBox="0 0 700 320"
      role="img"
      aria-label="Step-by-step authentication sequence diagram"
    ></svg>
    <div class="toolbar">
      <button id="change">Next message</button><span id="step" class="badge">STEP 1 OF 5</span>
    </div>
    <output id="status" class="status" aria-live="polite"></output>
  </section>
  <footer>Original diagram · local demonstration · no network requests</footer>
</main>

:root {
  --bg: #191429;
  --panel: #28203e;
  --text: #f0e7ff;
  --muted: #b6a6cf;
  --line: #483a62;
  --accent: #c5a4ff;
}
/* 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);
}

(() => {
  "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);
      }),
    );
  }

  let step = 0;
  const names = ["Browser", "Application", "Identity", "Session"],
    messages = [
      [0, 1, "Submit credentials"],
      [1, 2, "Verify password"],
      [2, 1, "Identity confirmed"],
      [1, 3, "Create session"],
      [1, 0, "Return secure cookie"],
    ];
  function draw() {
    const s = $("#chart");
    s.replaceChildren();
    const defs = svg("defs"),
      marker = svg("marker", {
        id: "arrow",
        viewBox: "0 0 10 10",
        refX: 9,
        refY: 5,
        markerWidth: 5,
        markerHeight: 5,
        orient: "auto",
      });
    marker.append(svg("path", { d: "M0 0L10 5 0 10Z", fill: "#839acc" }));
    defs.append(marker);
    s.append(defs);
    names.forEach((name, i) => {
      const x = 85 + i * 176;
      s.append(
        svg("rect", {
          x: x - 57,
          y: 5,
          width: 114,
          height: 36,
          rx: 7,
          fill: "var(--bg)",
          stroke: "var(--line)",
        }),
      );
      s.append(svg("text", { x, y: 28, "text-anchor": "middle", style: "fill:var(--text)" }, name));
      s.append(
        svg("line", {
          x1: x,
          y1: 42,
          x2: x,
          y2: 306,
          stroke: "var(--line)",
          "stroke-dasharray": "5 5",
        }),
      );
    });
    messages.forEach(([a, b, label], i) => {
      const y = 82 + i * 48,
        x1 = 85 + a * 176,
        x2 = 85 + b * 176,
        active = i === step;
      s.append(
        svg("line", {
          x1,
          y1: y,
          x2,
          y2: y,
          stroke: active ? "#cc9ddf" : "#839acc",
          "stroke-width": active ? 3 : 1.5,
          "marker-end": "url(#arrow)",
          opacity: i > step ? 0.2 : 1,
        }),
      );
      s.append(
        svg(
          "text",
          {
            x: (x1 + x2) / 2,
            y: y - 9,
            "text-anchor": "middle",
            style: "fill:" + (active ? "var(--accent)" : "var(--muted)"),
            opacity: i > step ? 0.3 : 1,
          },
          label,
        ),
      );
    });
    $("#step").textContent = "STEP " + (step + 1) + " OF 5";
  }
  $("#change").addEventListener("click", () => {
    step = (step + 1) % 5;
    draw();
    status(
      "Step " +
        (step + 1) +
        ": " +
        messages[step][2] +
        ". Diagram only; no credentials are collected.",
    );
  });
  draw();
})();