Pagine Facile

Wiki — Category / Portal Page

A dense, library-catalog category portal for a fictional distributed-systems wiki, built in a clean white knowledge-base palette. A header carries the category name, a serif description and live article counts, followed by a sticky A–Z jump bar, encyclopedic pages grouped under multi-column letter headings, a subcategory tile grid and a featured-article highlight card. The A–Z bar smooth-scrolls to letter groups, a search box live-filters every list, and a list/grid density toggle reflows the catalog. Inter, Source Serif 4, JetBrains Mono and vanilla JS only.

Apri in Lab

html css vanilla-js

Target: JS HTML

Codice

:root {
  --bg: #ffffff;
  --bg-2: #f7f8fa;
  --panel: #ffffff;
  --ink: #1a1a1f;
  --ink-2: #3a3a42;
  --muted: #6b7280;
  --line: rgba(20, 20, 30, 0.10);
  --line-2: rgba(20, 20, 30, 0.18);
  --link: #2563eb;
  --link-hover: #1d4ed8;
  --accent: #2563eb;
  --note: #2563eb;
  --tip: #16a34a;
  --warn: #d97706;
  --danger: #dc2626;
  --code-bg: #f4f4f6;
  --kbd-bg: #eceef2;
  --r-sm: 6px;
  --r-md: 10px;
  --r-lg: 14px;
  --sans: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
  --sidebar-w: 244px;
  --shadow-sm: 0 1px 2px rgba(20, 20, 30, 0.06);
  --shadow-md: 0 6px 22px rgba(20, 20, 30, 0.08);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

a { color: var(--link); text-decoration: none; }
a:hover { color: var(--link-hover); text-decoration: underline; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: var(--r-sm);
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 8px;
  background: var(--ink);
  color: #fff;
  padding: 8px 14px;
  border-radius: var(--r-sm);
  z-index: 60;
}
.skip-link:focus { left: 12px; }

/* ---------- Topbar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  gap: 16px;
  height: 56px;
  padding: 0 18px;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(1.4) blur(8px);
  border-bottom: 1px solid var(--line);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 38px;
  height: 38px;
  padding: 0 9px;
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: var(--r-sm);
  cursor: pointer;
}
.nav-toggle span {
  display: block;
  height: 2px;
  background: var(--ink-2);
  border-radius: 2px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 800;
  font-size: 17px;
  letter-spacing: -0.01em;
  color: var(--ink);
}
.brand:hover { text-decoration: none; }
.brand-mark { color: var(--accent); font-size: 14px; }
.brand-dim { color: var(--muted); font-weight: 600; }

.topbar-search {
  position: relative;
  flex: 1;
  max-width: 460px;
  margin-left: auto;
}
.topbar-search input {
  width: 100%;
  height: 38px;
  padding: 0 40px 0 14px;
  font: inherit;
  font-size: 14px;
  color: var(--ink);
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: 999px;
}
.topbar-search input:focus {
  background: #fff;
  border-color: var(--accent);
  outline: none;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.14);
}
.topbar-search kbd {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  pointer-events: none;
}

.topbar-links {
  display: flex;
  gap: 18px;
  font-size: 14px;
  font-weight: 500;
}
.topbar-links a { color: var(--ink-2); }

kbd {
  font-family: var(--mono);
  font-size: 11px;
  line-height: 1;
  padding: 3px 6px;
  color: var(--ink-2);
  background: var(--kbd-bg);
  border: 1px solid var(--line-2);
  border-bottom-width: 2px;
  border-radius: var(--r-sm);
}

/* ---------- Layout ---------- */
.layout {
  display: grid;
  grid-template-columns: var(--sidebar-w) minmax(0, 1fr);
  max-width: 1320px;
  margin: 0 auto;
}

.sidebar {
  position: sticky;
  top: 56px;
  align-self: start;
  height: calc(100vh - 56px);
  overflow-y: auto;
  padding: 22px 16px 40px;
  border-right: 1px solid var(--line);
  background: var(--bg);
}
.side-head {
  margin: 18px 8px 6px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}
.side-head:first-child { margin-top: 0; }
.side-list { list-style: none; margin: 0; padding: 0; }
.side-list a {
  display: block;
  padding: 6px 10px;
  border-radius: var(--r-sm);
  font-size: 14px;
  color: var(--ink-2);
}
.side-list a:hover { background: var(--bg-2); color: var(--ink); text-decoration: none; }
.side-list a[aria-current="page"] {
  background: rgba(37, 99, 235, 0.10);
  color: var(--link);
  font-weight: 600;
}

.sidebar-scrim {
  position: fixed;
  inset: 0;
  z-index: 30;
  background: rgba(20, 20, 30, 0.4);
}

/* ---------- Content ---------- */
.content {
  min-width: 0;
  padding: 26px clamp(18px, 4vw, 56px) 80px;
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  align-items: center;
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 18px;
}
.breadcrumb a { color: var(--ink-2); }
.breadcrumb [aria-current="page"] { color: var(--ink); font-weight: 600; }

.cat-header {
  padding-bottom: 22px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 30px;
}
.cat-kicker {
  margin: 0 0 6px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
}
.cat-title {
  margin: 0 0 12px;
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.1;
}
.cat-desc {
  max-width: 720px;
  margin: 0 0 18px;
  font-family: var(--serif);
  font-size: 17px;
  line-height: 1.65;
  color: var(--ink-2);
}
.cat-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 24px;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: 13px;
  color: var(--muted);
}
.cat-stats strong { color: var(--ink); font-weight: 700; }

.section-eyebrow {
  margin: 0 0 14px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

/* ---------- Featured ---------- */
.featured { margin-bottom: 38px; }
.featured-card {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr);
  gap: 0;
  background: linear-gradient(180deg, #fff, var(--bg-2));
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}
.featured-body { padding: 24px 26px; }
.badge {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.04em;
  padding: 3px 9px;
  border-radius: 999px;
}
.badge-star {
  color: var(--warn);
  background: rgba(217, 119, 6, 0.12);
  border: 1px solid rgba(217, 119, 6, 0.25);
}
.featured-body h2 {
  margin: 12px 0 10px;
  font-size: 24px;
  font-weight: 800;
  letter-spacing: -0.01em;
}
.featured-body p {
  margin: 0 0 12px;
  max-width: 56ch;
  font-family: var(--serif);
  font-size: 16px;
  line-height: 1.65;
  color: var(--ink-2);
}
.featured-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  font-family: var(--sans) !important;
  font-size: 12.5px !important;
  color: var(--muted) !important;
}
.featured-link { font-weight: 600; }
.featured-aside {
  display: flex;
  align-items: stretch;
  padding: 0;
  background: #f3f4f8;
  border-left: 1px solid var(--line);
}
.featured-aside pre {
  margin: 0;
  width: 100%;
  padding: 20px;
  overflow: auto;
}
.featured-aside code {
  font-family: var(--mono);
  font-size: 12.5px;
  line-height: 1.7;
  color: var(--ink-2);
  white-space: pre;
}

/* ---------- Subcategories ---------- */
.subcats { margin-bottom: 38px; }
.subcat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(210px, 1fr));
  gap: 12px;
}
.subcat {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 14px 16px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  transition: border-color 0.14s ease, transform 0.14s ease, box-shadow 0.14s ease;
}
.subcat:hover {
  text-decoration: none;
  border-color: var(--line-2);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}
.subcat-icon {
  font-size: 18px;
  color: var(--accent);
}
.subcat-name { font-weight: 600; color: var(--ink); }
.subcat-count { font-size: 12.5px; color: var(--muted); }

/* ---------- Articles ---------- */
.articles-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 14px;
}
.articles-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
}
.filter-box {
  position: relative;
  display: flex;
  align-items: center;
  gap: 8px;
}
.filter-box input {
  height: 36px;
  width: 220px;
  max-width: 50vw;
  padding: 0 12px;
  font: inherit;
  font-size: 14px;
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: var(--r-sm);
  color: var(--ink);
}
.filter-box input:focus {
  background: #fff;
  border-color: var(--accent);
  outline: none;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.14);
}
.filter-count { font-size: 12.5px; color: var(--muted); }

.density-toggle {
  display: inline-flex;
  padding: 3px;
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: var(--r-sm);
}
.density-toggle button {
  font: inherit;
  font-size: 13px;
  font-weight: 600;
  padding: 5px 12px;
  border: none;
  background: transparent;
  color: var(--ink-2);
  border-radius: 4px;
  cursor: pointer;
}
.density-toggle button.is-active {
  background: #fff;
  color: var(--ink);
  box-shadow: var(--shadow-sm);
}

/* A–Z bar */
.az-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  padding: 10px 12px;
  margin-bottom: 24px;
  background: var(--bg-2);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  position: sticky;
  top: 56px;
  z-index: 20;
}
.az-bar button {
  font-family: var(--mono);
  font-size: 12.5px;
  font-weight: 500;
  width: 28px;
  height: 28px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid transparent;
  background: transparent;
  color: var(--ink-2);
  border-radius: var(--r-sm);
  cursor: pointer;
  transition: background 0.12s ease, color 0.12s ease;
}
.az-bar button:hover:not(:disabled) {
  background: #fff;
  border-color: var(--line);
  color: var(--link);
}
.az-bar button.is-active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.az-bar button:disabled {
  color: var(--line-2);
  cursor: default;
}

/* Letter groups */
.article-groups { display: flex; flex-direction: column; gap: 30px; }
.letter-group { scroll-margin-top: 100px; }
.letter-group.is-hidden { display: none; }
.letter-head {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin: 0 0 12px;
  padding-bottom: 6px;
  border-bottom: 2px solid var(--line);
}
.letter-head .letter {
  font-size: 22px;
  font-weight: 800;
  color: var(--accent);
  font-family: var(--mono);
}
.letter-head .letter-meta { font-size: 12.5px; color: var(--muted); }

.article-list {
  list-style: none;
  margin: 0;
  padding: 0;
  columns: 3;
  column-gap: 28px;
}
.article-list li {
  break-inside: avoid;
  margin-bottom: 4px;
}
.article-list li.is-hidden { display: none; }
.article-list a {
  display: block;
  padding: 4px 8px;
  border-radius: var(--r-sm);
  color: var(--link);
  line-height: 1.5;
}
.article-list a:hover { background: var(--bg-2); text-decoration: none; }
.article-list .art-tag {
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--muted);
  margin-left: 6px;
}

/* Grid density view */
.article-groups.is-grid .article-list {
  columns: auto;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 8px;
}
.article-groups.is-grid .article-list a {
  border: 1px solid var(--line);
  background: var(--panel);
  padding: 10px 12px;
  border-radius: var(--r-md);
  font-weight: 500;
}
.article-groups.is-grid .article-list a:hover {
  border-color: var(--line-2);
  box-shadow: var(--shadow-sm);
}

.no-results {
  padding: 28px;
  text-align: center;
  color: var(--muted);
  font-size: 15px;
  background: var(--bg-2);
  border: 1px dashed var(--line-2);
  border-radius: var(--r-md);
}

.cat-footer {
  margin-top: 56px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
  font-size: 12.5px;
  color: var(--muted);
}

/* ---------- Toast ---------- */
.toast {
  position: fixed;
  left: 50%;
  bottom: 26px;
  transform: translateX(-50%) translateY(16px);
  background: var(--ink);
  color: #fff;
  font-size: 13.5px;
  font-weight: 500;
  padding: 10px 18px;
  border-radius: 999px;
  box-shadow: var(--shadow-md);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.22s ease, transform 0.22s ease;
  z-index: 70;
}
.toast.is-show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ---------- Responsive ---------- */
@media (max-width: 1040px) {
  .article-list { columns: 2; }
}

@media (max-width: 820px) {
  .nav-toggle { display: flex; }
  .layout { grid-template-columns: minmax(0, 1fr); }
  .sidebar {
    position: fixed;
    top: 56px;
    left: 0;
    z-index: 35;
    width: 280px;
    max-width: 84vw;
    height: calc(100vh - 56px);
    transform: translateX(-102%);
    transition: transform 0.22s ease;
    box-shadow: var(--shadow-md);
  }
  .sidebar.is-open { transform: translateX(0); }
  .topbar-links { display: none; }
  .featured-card { grid-template-columns: minmax(0, 1fr); }
  .featured-aside { border-left: none; border-top: 1px solid var(--line); }
}

@media (max-width: 520px) {
  .topbar { gap: 10px; padding: 0 12px; }
  .brand-name { display: none; }
  .article-list, .article-groups.is-grid .article-list { columns: auto; display: block; }
  .article-groups.is-grid .article-list { display: flex; flex-direction: column; }
  .az-bar { position: static; }
  .articles-bar { flex-direction: column; align-items: stretch; }
  .filter-box input { width: 100%; max-width: none; }
}

@media (prefers-reduced-motion: reduce) {
  * { scroll-behavior: auto !important; transition: none !important; }
}

(function () {
  "use strict";

  /* ---------- Data: fictional but real-feeling distributed-systems articles ---------- */
  var ARTICLES = [
    { t: "Aurora DB", tag: "system" },
    { t: "Acceptor Quorum", tag: "concept" },
    { t: "Anti-Entropy Repair", tag: "concept" },
    { t: "Append-Only Log", tag: "concept" },
    { t: "Bloom Filter Index", tag: "structure" },
    { t: "Byzantine Fault Tolerance", tag: "concept" },
    { t: "Backpressure Control", tag: "concept" },
    { t: "Bucket Sharding", tag: "concept" },
    { t: "CAP Theorem", tag: "theorem" },
    { t: "Causal Consistency", tag: "model" },
    { t: "Chandy–Lamport Snapshot", tag: "algorithm" },
    { t: "Consistent Hashing", tag: "algorithm" },
    { t: "Compaction Strategy", tag: "concept" },
    { t: "Distributed Lock", tag: "primitive" },
    { t: "Dynamo Replication", tag: "system" },
    { t: "Delta CRDT", tag: "structure" },
    { t: "Epoch Fencing", tag: "concept" },
    { t: "Eventual Consistency", tag: "model" },
    { t: "Exactly-Once Delivery", tag: "concept" },
    { t: "Failure Detector", tag: "primitive" },
    { t: "Flow-Control Window", tag: "concept" },
    { t: "Gossip Protocol", tag: "protocol" },
    { t: "Gray Failure", tag: "concept" },
    { t: "Hinted Handoff", tag: "concept" },
    { t: "Heartbeat Lease", tag: "primitive" },
    { t: "Idempotency Key", tag: "concept" },
    { t: "Invariant Confluence", tag: "theory" },
    { t: "Jepsen Test Harness", tag: "tooling" },
    { t: "Kafka Partition Log", tag: "system" },
    { t: "Lamport Timestamp", tag: "concept" },
    { t: "Leaderless Replication", tag: "concept" },
    { t: "Linearizability", tag: "model" },
    { t: "Log-Structured Merge Tree", tag: "structure" },
    { t: "Merkle Tree Sync", tag: "structure" },
    { t: "Multi-Paxos", tag: "algorithm" },
    { t: "Membership Protocol", tag: "protocol" },
    { t: "Network Partition", tag: "concept" },
    { t: "Nimbus Scheduler", tag: "system" },
    { t: "Optimistic Concurrency", tag: "concept" },
    { t: "Operation Transform", tag: "algorithm" },
    { t: "Paxos", tag: "algorithm" },
    { t: "Phi Accrual Detector", tag: "algorithm" },
    { t: "Primary-Backup Replication", tag: "concept" },
    { t: "Quorum Reads", tag: "concept" },
    { t: "Quiescent Consistency", tag: "model" },
    { t: "Raft Consensus", tag: "algorithm" },
    { t: "Read Repair", tag: "concept" },
    { t: "Replication Lag", tag: "concept" },
    { t: "Saga Pattern", tag: "pattern" },
    { t: "Sequential Consistency", tag: "model" },
    { t: "Split-Brain", tag: "concept" },
    { t: "State Machine Replication", tag: "concept" },
    { t: "Two-Phase Commit", tag: "protocol" },
    { t: "Tunable Consistency", tag: "concept" },
    { t: "Vector Clock", tag: "structure" },
    { t: "Verdant Stack", tag: "system" },
    { t: "View Synchrony", tag: "concept" },
    { t: "Write-Ahead Log", tag: "structure" },
    { t: "Witness Replica", tag: "concept" },
    { t: "Zab Protocol", tag: "protocol" },
    { t: "Zone-Aware Routing", tag: "concept" }
  ];

  var ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".split("");

  var groupsEl = document.getElementById("articleGroups");
  var azBar = document.getElementById("azBar");
  var filterInput = document.getElementById("articleFilter");
  var filterCount = document.getElementById("filterCount");
  var noResults = document.getElementById("noResults");
  var statArticles = document.getElementById("statArticles");

  /* ---------- Build grouped article lists ---------- */
  var byLetter = {};
  ALPHABET.forEach(function (l) { byLetter[l] = []; });
  ARTICLES.forEach(function (a) {
    var letter = a.t[0].toUpperCase();
    if (!byLetter[letter]) byLetter[letter] = [];
    byLetter[letter].push(a);
  });
  Object.keys(byLetter).forEach(function (l) {
    byLetter[l].sort(function (x, y) { return x.t.localeCompare(y.t); });
  });

  statArticles.textContent = String(ARTICLES.length);

  function buildGroups() {
    var frag = document.createDocumentFragment();
    ALPHABET.forEach(function (letter) {
      var items = byLetter[letter];
      if (!items || !items.length) return;

      var group = document.createElement("section");
      group.className = "letter-group";
      group.id = "letter-" + letter;
      group.setAttribute("aria-labelledby", "head-" + letter);

      var head = document.createElement("div");
      head.className = "letter-head";
      head.id = "head-" + letter;
      head.innerHTML =
        '<span class="letter">' + letter + "</span>" +
        '<span class="letter-meta">' + items.length +
        (items.length === 1 ? " page" : " pages") + "</span>";
      group.appendChild(head);

      var ul = document.createElement("ul");
      ul.className = "article-list";
      items.forEach(function (a) {
        var li = document.createElement("li");
        var link = document.createElement("a");
        link.href = "#";
        link.dataset.title = a.t.toLowerCase();
        link.innerHTML =
          escapeHtml(a.t) +
          '<span class="art-tag">' + escapeHtml(a.tag) + "</span>";
        link.addEventListener("click", function (e) {
          e.preventDefault();
          toast("Opening “" + a.t + "”");
        });
        li.appendChild(link);
        ul.appendChild(li);
      });
      group.appendChild(ul);
      frag.appendChild(group);
    });
    groupsEl.appendChild(frag);
  }

  function escapeHtml(s) {
    return s.replace(/[&<>"']/g, function (c) {
      return { "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;" }[c];
    });
  }

  /* ---------- A–Z jump bar ---------- */
  function buildAzBar() {
    var frag = document.createDocumentFragment();
    var allBtn = document.createElement("button");
    allBtn.type = "button";
    allBtn.textContent = "All";
    allBtn.style.width = "auto";
    allBtn.style.padding = "0 10px";
    allBtn.className = "is-active";
    allBtn.dataset.letter = "ALL";
    frag.appendChild(allBtn);

    ALPHABET.forEach(function (letter) {
      var btn = document.createElement("button");
      btn.type = "button";
      btn.textContent = letter;
      btn.dataset.letter = letter;
      if (!byLetter[letter] || !byLetter[letter].length) {
        btn.disabled = true;
      }
      frag.appendChild(btn);
    });
    azBar.appendChild(frag);

    azBar.addEventListener("click", function (e) {
      var btn = e.target.closest("button");
      if (!btn || btn.disabled) return;
      setActiveLetter(btn.dataset.letter);
    });
  }

  function setActiveLetter(letter) {
    azBar.querySelectorAll("button").forEach(function (b) {
      b.classList.toggle("is-active", b.dataset.letter === letter);
    });
    if (letter === "ALL") {
      groupsEl.querySelector(".letter-group");
      window.scrollTo({ top: groupsEl.offsetTop - 100, behavior: "smooth" });
      return;
    }
    var target = document.getElementById("letter-" + letter);
    if (target) {
      target.scrollIntoView({ behavior: "smooth", block: "start" });
      target.querySelector(".letter").animate(
        [{ transform: "scale(1)" }, { transform: "scale(1.18)" }, { transform: "scale(1)" }],
        { duration: 360, easing: "ease-out" }
      );
    }
  }

  /* ---------- Live filter ---------- */
  var filterTimer = null;
  function applyFilter(q) {
    q = q.trim().toLowerCase();
    var shown = 0;
    var groups = groupsEl.querySelectorAll(".letter-group");
    groups.forEach(function (group) {
      var visibleInGroup = 0;
      group.querySelectorAll(".article-list li").forEach(function (li) {
        var title = li.querySelector("a").dataset.title;
        var match = !q || title.indexOf(q) !== -1;
        li.classList.toggle("is-hidden", !match);
        if (match) { visibleInGroup++; shown++; }
      });
      group.classList.toggle("is-hidden", visibleInGroup === 0);
    });

    noResults.hidden = shown !== 0;

    if (q) {
      filterCount.textContent = shown + (shown === 1 ? " match" : " matches");
    } else {
      filterCount.textContent = "";
    }

    // disable A–Z buttons whose group is now empty
    azBar.querySelectorAll("button").forEach(function (b) {
      var letter = b.dataset.letter;
      if (letter === "ALL") return;
      var g = document.getElementById("letter-" + letter);
      var hasVisible = g && !g.classList.contains("is-hidden");
      var emptyData = !byLetter[letter] || !byLetter[letter].length;
      b.disabled = emptyData || !hasVisible;
    });
  }

  filterInput.addEventListener("input", function () {
    var v = filterInput.value;
    clearTimeout(filterTimer);
    filterTimer = setTimeout(function () { applyFilter(v); }, 80);
  });

  /* ---------- Density toggle ---------- */
  var viewList = document.getElementById("viewList");
  var viewGrid = document.getElementById("viewGrid");

  function setDensity(grid) {
    groupsEl.classList.toggle("is-grid", grid);
    viewGrid.classList.toggle("is-active", grid);
    viewList.classList.toggle("is-active", !grid);
    viewGrid.setAttribute("aria-pressed", String(grid));
    viewList.setAttribute("aria-pressed", String(!grid));
    toast(grid ? "Grid view" : "List view");
  }
  viewList.addEventListener("click", function () { setDensity(false); });
  viewGrid.addEventListener("click", function () { setDensity(true); });

  /* ---------- Sidebar drawer ---------- */
  var navToggle = document.getElementById("navToggle");
  var sidebar = document.getElementById("sidebar");
  var scrim = document.getElementById("scrim");

  function openNav(open) {
    sidebar.classList.toggle("is-open", open);
    scrim.hidden = !open;
    navToggle.setAttribute("aria-expanded", String(open));
  }
  navToggle.addEventListener("click", function () {
    openNav(!sidebar.classList.contains("is-open"));
  });
  scrim.addEventListener("click", function () { openNav(false); });
  sidebar.addEventListener("click", function (e) {
    if (e.target.closest("a") && window.matchMedia("(max-width: 820px)").matches) {
      openNav(false);
    }
  });

  /* ---------- Toast helper ---------- */
  var toastEl = document.getElementById("toast");
  var toastTimer = null;
  function toast(msg) {
    toastEl.textContent = msg;
    toastEl.classList.add("is-show");
    clearTimeout(toastTimer);
    toastTimer = setTimeout(function () {
      toastEl.classList.remove("is-show");
    }, 1800);
  }

  /* ---------- Keyboard shortcuts ---------- */
  var topSearch = document.getElementById("topSearch");
  document.addEventListener("keydown", function (e) {
    var typing = /^(INPUT|TEXTAREA)$/.test(document.activeElement.tagName);
    if (e.key === "/" && !typing) {
      e.preventDefault();
      topSearch.focus();
      topSearch.select();
    } else if (e.key === "Escape") {
      if (sidebar.classList.contains("is-open")) openNav(false);
      if (document.activeElement === filterInput && filterInput.value) {
        filterInput.value = "";
        applyFilter("");
      }
    }
  });

  // mirror top search into the in-page filter for convenience
  topSearch.addEventListener("input", function () {
    filterInput.value = topSearch.value;
    applyFilter(topSearch.value);
    if (topSearch.value) {
      document.getElementById("articleFilter")
        .scrollIntoView({ behavior: "smooth", block: "center" });
    }
  });

  /* ---------- Init ---------- */
  buildGroups();
  buildAzBar();
})();

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <title>Category: Distributed Systems — Codex Wiki</title>
  <link rel="preconnect" href="https://fonts.googleapis.com" />
  <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />
  <link href="https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&family=Source+Serif+4:opsz,[email protected],400;8..60,500;8..60,600&family=JetBrains+Mono:wght@400;500&display=swap" rel="stylesheet" />
  <link rel="stylesheet" href="style.css" />
</head>
<body>
  <a class="skip-link" href="#main">Skip to content</a>

  <header class="topbar">
    <button class="nav-toggle" id="navToggle" aria-label="Toggle navigation" aria-expanded="false" aria-controls="sidebar">
      <span></span><span></span><span></span>
    </button>
    <a class="brand" href="#" aria-label="Codex Wiki home">
      <span class="brand-mark" aria-hidden="true">◆</span>
      <span class="brand-name">Codex<span class="brand-dim">Wiki</span></span>
    </a>
    <div class="topbar-search">
      <input type="search" id="topSearch" placeholder="Search the wiki…  (press /)" aria-label="Search the wiki" autocomplete="off" />
      <kbd>/</kbd>
    </div>
    <nav class="topbar-links" aria-label="Utility">
      <a href="#">Random</a>
      <a href="#">Recent</a>
      <a href="#">Help</a>
    </nav>
  </header>

  <div class="layout">
    <aside class="sidebar" id="sidebar" aria-label="Site navigation">
      <nav>
        <p class="side-head">Browse</p>
        <ul class="side-list">
          <li><a href="#">All categories</a></li>
          <li><a href="#" aria-current="page">Distributed Systems</a></li>
          <li><a href="#">Storage Engines</a></li>
          <li><a href="#">Networking</a></li>
          <li><a href="#">Cryptography</a></li>
          <li><a href="#">Observability</a></li>
        </ul>
        <p class="side-head">Featured portals</p>
        <ul class="side-list">
          <li><a href="#">Aurora DB</a></li>
          <li><a href="#">Project Nimbus</a></li>
          <li><a href="#">The Verdant Stack</a></li>
        </ul>
        <p class="side-head">Tools</p>
        <ul class="side-list">
          <li><a href="#">What links here</a></li>
          <li><a href="#">Category tree</a></li>
          <li><a href="#">Export catalog</a></li>
        </ul>
      </nav>
    </aside>
    <div class="sidebar-scrim" id="scrim" hidden></div>

    <main class="content" id="main">
      <nav class="breadcrumb" aria-label="Breadcrumb">
        <a href="#">Home</a>
        <span aria-hidden="true">/</span>
        <a href="#">Categories</a>
        <span aria-hidden="true">/</span>
        <span aria-current="page">Distributed Systems</span>
      </nav>

      <header class="cat-header">
        <p class="cat-kicker">Category portal</p>
        <h1 class="cat-title">Distributed Systems</h1>
        <p class="cat-desc">
          Articles on consensus, replication, partitioning, fault tolerance and the
          engineering trade-offs of running software across many unreliable machines. This portal
          collects encyclopedic entries, design notes and protocol references for systems such as
          <a href="#">Aurora DB</a>, <a href="#">Project Nimbus</a> and the <a href="#">Verdant&nbsp;Stack</a>.
        </p>
        <ul class="cat-stats" aria-label="Category statistics">
          <li><strong id="statArticles">42</strong> articles</li>
          <li><strong>9</strong> subcategories</li>
          <li><strong>1.2k</strong> revisions</li>
          <li><strong>Updated</strong> 2 days ago</li>
        </ul>
      </header>

      <section class="featured" aria-labelledby="featured-h">
        <p class="section-eyebrow" id="featured-h">Featured article</p>
        <article class="featured-card">
          <div class="featured-body">
            <span class="badge badge-star" aria-hidden="true">★ Featured</span>
            <h2><a href="#">The Raft Consensus Protocol</a></h2>
            <p>
              Raft is a consensus algorithm designed to be more understandable than Paxos. It
              decomposes the problem into <em>leader election</em>, <em>log replication</em> and
              <em>safety</em>, and underpins the replication layer of Aurora DB. A single elected
              leader accepts client writes, appends them to a durable log, and replicates entries to
              follower nodes; an entry commits once a majority acknowledge it.
            </p>
            <p class="featured-meta">
              <span>12,400 words</span><span aria-hidden="true">·</span>
              <span>Reviewed by 6 editors</span><span aria-hidden="true">·</span>
              <span>Last edited 2026-06-06</span>
            </p>
            <a class="featured-link" href="#">Read the full article →</a>
          </div>
          <div class="featured-aside" aria-hidden="true">
            <pre><code>state := FOLLOWER
on election_timeout:
  state := CANDIDATE
  term  := term + 1
  vote_for_self()
  request_votes()
  if votes &gt; quorum:
    state := LEADER</code></pre>
          </div>
        </article>
      </section>

      <section class="subcats" aria-labelledby="subcats-h">
        <p class="section-eyebrow" id="subcats-h">Subcategories</p>
        <div class="subcat-grid">
          <a class="subcat" href="#"><span class="subcat-icon" aria-hidden="true">⇄</span><span class="subcat-name">Consensus &amp; Coordination</span><span class="subcat-count">8 articles</span></a>
          <a class="subcat" href="#"><span class="subcat-icon" aria-hidden="true">⧉</span><span class="subcat-name">Replication</span><span class="subcat-count">7 articles</span></a>
          <a class="subcat" href="#"><span class="subcat-icon" aria-hidden="true">▦</span><span class="subcat-name">Partitioning &amp; Sharding</span><span class="subcat-count">6 articles</span></a>
          <a class="subcat" href="#"><span class="subcat-icon" aria-hidden="true">⏱</span><span class="subcat-name">Clocks &amp; Ordering</span><span class="subcat-count">5 articles</span></a>
          <a class="subcat" href="#"><span class="subcat-icon" aria-hidden="true">⚠</span><span class="subcat-name">Fault Tolerance</span><span class="subcat-count">9 articles</span></a>
          <a class="subcat" href="#"><span class="subcat-icon" aria-hidden="true">◷</span><span class="subcat-name">Latency &amp; Scheduling</span><span class="subcat-count">4 articles</span></a>
        </div>
      </section>

      <section class="articles-section" aria-labelledby="articles-h">
        <div class="articles-bar">
          <p class="section-eyebrow" id="articles-h">Pages in this category</p>
          <div class="articles-controls">
            <div class="filter-box">
              <input type="search" id="articleFilter" placeholder="Filter pages…" aria-label="Filter pages in this category" autocomplete="off" />
              <span class="filter-count" id="filterCount" aria-live="polite"></span>
            </div>
            <div class="density-toggle" role="group" aria-label="View density">
              <button type="button" id="viewList" class="is-active" aria-pressed="true">List</button>
              <button type="button" id="viewGrid" aria-pressed="false">Grid</button>
            </div>
          </div>
        </div>

        <nav class="az-bar" id="azBar" aria-label="Jump to letter">
          <!-- buttons injected by script.js -->
        </nav>

        <div class="article-groups" id="articleGroups">
          <!-- groups injected by script.js -->
        </div>

        <p class="no-results" id="noResults" hidden>No pages match that filter.</p>
      </section>

      <footer class="cat-footer">
        <p>Codex Wiki · text available under a fictional open license · this is an illustrative demo.</p>
      </footer>
    </main>
  </div>

  <div class="toast" id="toast" role="status" aria-live="polite"></div>

  <script src="script.js"></script>
</body>
</html>

Category / Portal Page

A complete wiki category portal for Distributed Systems, laid out in a crisp white docs palette with a persistent left sidebar, a readable centered column and a high-density, library-catalog feel. The header pairs the category name with a serif description and a row of live statistics — article count, subcategories, revisions and last-updated — above a featured-article highlight card and a grid of linked subcategory tiles. Below them, every page in the category is grouped alphabetically under large letter headings in multi-column lists, each entry tagged with its kind (algorithm, protocol, model, structure…).

The interactions are all vanilla JS. A sticky A–Z bar smooth-scrolls to the matching letter group and pulses the heading on arrival, with letters that have no pages disabled automatically. A search box live-filters every list as you type — hiding non-matching entries, collapsing empty letter groups, updating a match counter and disabling the A–Z buttons whose groups went empty. A list/grid toggle reflows the catalog between tight multi-column lists and a card grid, and the top-bar search mirrors straight into the in-page filter.

The layout is fully responsive: the sidebar collapses to a drawer with a scrim below 820px, the multi-column lists step down to two and then one column, and the A–Z bar unsticks on the narrowest screens. Keyboard shortcuts (/ to focus search, Esc to clear or close the drawer), visible focus rings, semantic landmarks, a small toast() helper and prefers-reduced-motion support round it out — no frameworks, no build step.

Illustrative UI only — fictional articles, products, and data.