:root {
  --bg-deep: #060a12;
  --bg-mid: #0b1220;
  --bg-card: #111a2b;
  --bg-card-hover: #162235;
  --border: #1c3558;
  --border-soft: rgba(28, 53, 88, 0.6);
  --accent: #00e6b8;
  --accent-dim: #00b894;
  --accent-glow: rgba(0, 230, 184, 0.18);
  --accent-2: #5b8cff;
  --text: #e8eef7;
  --text-muted: #8ea0b8;
  --warning: #f5a524;
  --danger: #ff5c7a;
  --info: #4cc9f0;
  --qos0: #7b8a9e;
  --qos1: #f5a524;
  --qos2: #ff5c7a;
  --font-mono: "JetBrains Mono", "Fira Code", "Consolas", monospace;
  --font-sans: "Inter", "Segoe UI", system-ui, sans-serif;
  --radius: 14px;
  --shadow: 0 20px 50px rgba(0, 0, 0, 0.35);
  --max: 980px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-deep);
  color: var(--text);
  line-height: 1.75;
  min-height: 100vh;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 50% at 20% -10%, rgba(0, 230, 184, 0.12), transparent 55%),
    radial-gradient(ellipse 60% 40% at 90% 10%, rgba(91, 140, 255, 0.1), transparent 50%),
    linear-gradient(rgba(0, 230, 184, 0.025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 230, 184, 0.025) 1px, transparent 1px);
  background-size: auto, auto, 48px 48px, 48px 48px;
  pointer-events: none;
  z-index: 0;
}

/* Header */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(6, 10, 18, 0.8);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-soft);
  padding: 0.9rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--text);
}

.logo-icon {
  width: 38px;
  height: 38px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.75rem;
  color: var(--bg-deep);
  box-shadow: 0 0 20px var(--accent-glow);
}

.logo-text {
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: -0.02em;
}

.logo-text span {
  color: var(--accent);
}

nav {
  display: flex;
  gap: 0.35rem;
  flex-wrap: wrap;
  justify-content: flex-end;
}

nav a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.8rem;
  font-weight: 500;
  padding: 0.4rem 0.7rem;
  border-radius: 999px;
  transition: color 0.2s, background 0.2s;
}

nav a:hover {
  color: var(--accent);
  background: var(--accent-glow);
}

/* Hero */
.hero {
  position: relative;
  z-index: 1;
  padding: 4.5rem 1.5rem 3rem;
  max-width: var(--max);
  margin: 0 auto;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 2rem;
  align-items: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  background: var(--accent-glow);
  border: 1px solid rgba(0, 230, 184, 0.35);
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  padding: 0.4rem 0.9rem;
  border-radius: 999px;
  margin-bottom: 1.25rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero h1 {
  font-size: clamp(2.2rem, 5vw, 3.4rem);
  font-weight: 800;
  line-height: 1.12;
  letter-spacing: -0.03em;
  margin-bottom: 1rem;
}

.hero h1 em {
  font-style: normal;
  background: linear-gradient(120deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-lead {
  color: var(--text-muted);
  font-size: 1.1rem;
  max-width: 34rem;
  margin-bottom: 1.75rem;
}

.hero-stats {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.stat {
  background: rgba(17, 26, 43, 0.8);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0.85rem 1.1rem;
  min-width: 110px;
}

.stat-value {
  font-family: var(--font-mono);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--accent);
}

.stat-label {
  font-size: 0.7rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-top: 0.15rem;
}

.hero-panel {
  background: linear-gradient(160deg, rgba(17, 26, 43, 0.95), rgba(11, 18, 32, 0.9));
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 1.25rem;
  box-shadow: var(--shadow);
  font-family: var(--font-mono);
  font-size: 0.78rem;
}

.hero-panel-title {
  color: var(--text-muted);
  margin-bottom: 0.85rem;
  display: flex;
  justify-content: space-between;
}

.hero-panel-title span {
  color: var(--accent);
}

.packet-line {
  display: flex;
  gap: 0.6rem;
  padding: 0.35rem 0;
  border-bottom: 1px solid rgba(28, 53, 88, 0.45);
}

.packet-line:last-child {
  border-bottom: none;
}

.packet-tag {
  color: var(--accent-2);
  min-width: 4.5rem;
}

.packet-msg {
  color: var(--accent);
}

/* Layout */
main {
  position: relative;
  z-index: 1;
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 1.5rem 5rem;
}

.toc {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 0.75rem;
  margin-bottom: 3rem;
}

.toc a {
  text-decoration: none;
  color: var(--text-muted);
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0.9rem 1rem;
  transition: border-color 0.2s, transform 0.2s, color 0.2s;
}

.toc a:hover {
  border-color: var(--accent-dim);
  color: var(--text);
  transform: translateY(-2px);
}

.toc-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--accent);
  margin-bottom: 0.25rem;
}

.toc-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: inherit;
}

section {
  margin-bottom: 3.5rem;
  scroll-margin-top: 5rem;
}

section h2 {
  font-size: 1.65rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

section h2 .section-num {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent);
  background: var(--accent-glow);
  padding: 0.25rem 0.55rem;
  border-radius: 6px;
}

section h3 {
  font-size: 1.15rem;
  margin: 1.75rem 0 0.75rem;
  color: var(--text);
  letter-spacing: -0.01em;
}

section h4 {
  font-size: 1rem;
  margin: 1.1rem 0 0.5rem;
}

section p,
.lead {
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.lead {
  font-size: 1.05rem;
}

section ul,
section ol {
  color: var(--text-muted);
  padding-left: 1.35rem;
  margin-bottom: 1rem;
}

section li {
  margin-bottom: 0.45rem;
}

.callout {
  background: linear-gradient(135deg, rgba(0, 230, 184, 0.08), rgba(91, 140, 255, 0.06));
  border: 1px solid rgba(0, 230, 184, 0.25);
  border-left: 3px solid var(--accent);
  border-radius: 12px;
  padding: 1rem 1.2rem;
  margin: 1.25rem 0;
  color: var(--text-muted);
}

.callout strong {
  color: var(--text);
}

.compare-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin: 1.25rem 0;
}

.compare-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
}

.compare-card.http {
  border-top: 3px solid var(--warning);
}

.compare-card.mqtt {
  border-top: 3px solid var(--accent);
}

.compare-card h4 {
  margin-top: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.compare-card ul {
  margin-bottom: 0;
  padding-left: 1.1rem;
}

.badge {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  padding: 0.2rem 0.45rem;
  border-radius: 4px;
}

.badge-warn {
  background: rgba(245, 165, 36, 0.15);
  color: var(--warning);
}

.badge-ok {
  background: var(--accent-glow);
  color: var(--accent);
}

/* Cards */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.35rem;
  margin-bottom: 1rem;
  transition: border-color 0.2s, background 0.2s, transform 0.2s;
}

.card:hover {
  border-color: rgba(0, 230, 184, 0.35);
  background: var(--bg-card-hover);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin: 1.1rem 0;
}

.card-icon {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-glow);
  color: var(--accent);
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.85rem;
  margin-bottom: 0.75rem;
}

.card h4 {
  font-size: 1rem;
  margin: 0 0 0.45rem;
}

.card p {
  font-size: 0.9rem;
  margin: 0;
}

/* Code */
pre {
  background: #080d16;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0;
  overflow-x: auto;
  margin: 1rem 0;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.65;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.02);
}

pre.code-block {
  padding: 0;
}

pre code {
  display: block;
  padding: 1.1rem 1.25rem;
  background: transparent !important;
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
}

/* Prism — MQTT-tema tokens */
code[class*="language-"],
pre[class*="language-"] {
  text-shadow: none;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
}

pre[class*="language-"] {
  margin: 1rem 0;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: #080d16 !important;
}

:not(pre) > code {
  background: rgba(0, 230, 184, 0.1);
  color: var(--accent);
  padding: 0.15rem 0.4rem;
  border-radius: 5px;
}

.token.comment,
.token.prolog,
.token.doctype,
.token.cdata {
  color: #6b7f99;
  font-style: italic;
}

.token.punctuation {
  color: #8ea0b8;
}

.token.property,
.token.tag,
.token.boolean,
.token.number,
.token.constant,
.token.symbol {
  color: #f5a524;
}

.token.selector,
.token.attr-name,
.token.string,
.token.char,
.token.builtin,
.token.inserted {
  color: var(--accent);
}

.token.operator,
.token.entity,
.token.url,
.language-css .token.string,
.style .token.string {
  color: #4cc9f0;
}

.token.atrule,
.token.attr-value,
.token.keyword {
  color: var(--accent-2);
}

.token.function,
.token.class-name {
  color: #c792ea;
}

.token.regex,
.token.important,
.token.variable {
  color: #ff5c7a;
}

.token.deleted {
  color: var(--danger);
}

/* Topic tree */
.topic-tree {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  background: #080d16;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.25rem;
  margin: 1rem 0;
}

.topic-tree .root {
  color: var(--accent);
  font-weight: 700;
}

.topic-tree .branch {
  color: var(--text-muted);
  padding-left: 1.5rem;
  border-left: 1px dashed var(--border);
  margin-left: 0.5rem;
}

.topic-tree .leaf {
  color: var(--info);
}

/* QoS */
.qos-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  margin-right: 0.5rem;
}

.qos-0 { background: rgba(123, 138, 158, 0.2); color: var(--qos0); }
.qos-1 { background: rgba(245, 165, 36, 0.2); color: var(--qos1); }
.qos-2 { background: rgba(255, 92, 122, 0.2); color: var(--qos2); }

.qos-flow {
  display: grid;
  gap: 0.75rem;
  margin: 1rem 0 1.5rem;
}

.qos-step {
  display: grid;
  grid-template-columns: 90px 1fr;
  gap: 0.75rem;
  align-items: start;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.85rem 1rem;
}

.qos-step code {
  font-size: 0.75rem;
}

/* Diagram */
.diagram {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
  flex-wrap: wrap;
  padding: 1.75rem 1rem;
  margin: 1.5rem 0;
  background: rgba(8, 13, 22, 0.6);
  border: 1px solid var(--border);
  border-radius: 16px;
}

.diagram-box {
  background: var(--bg-card);
  border: 2px solid var(--border);
  border-radius: 12px;
  padding: 1rem 1.2rem;
  text-align: center;
  min-width: 120px;
}

.diagram-box.broker {
  border-color: var(--accent);
  box-shadow: 0 0 28px var(--accent-glow);
}

.diagram-box .label {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.diagram-box .name {
  font-weight: 700;
  margin-top: 0.25rem;
}

.diagram-arrow {
  color: var(--accent);
  font-size: 1.5rem;
  padding: 0 0.5rem;
}

.diagram-arrow .sub {
  display: block;
  font-size: 0.65rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.packet-table td:first-child {
  font-family: var(--font-mono);
  color: var(--accent);
  white-space: nowrap;
}

/* Timeline */
.timeline {
  border-left: 2px solid var(--border);
  margin: 1.25rem 0 1.25rem 0.5rem;
  padding-left: 1.25rem;
}

.timeline-item {
  position: relative;
  margin-bottom: 1.25rem;
}

.timeline-item::before {
  content: "";
  position: absolute;
  left: -1.55rem;
  top: 0.4rem;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-glow);
}

.timeline-item strong {
  display: block;
  color: var(--text);
  margin-bottom: 0.2rem;
}

.timeline-item p {
  margin: 0;
  font-size: 0.92rem;
}

/* Demo panel */
.demo-panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  overflow: hidden;
  margin: 1.5rem 0;
  box-shadow: var(--shadow);
}

.demo-header {
  background: linear-gradient(90deg, rgba(0, 230, 184, 0.1), rgba(91, 140, 255, 0.08));
  border-bottom: 1px solid var(--border);
  padding: 0.85rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.demo-header h3 {
  margin: 0;
  font-size: 0.95rem;
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--danger);
  display: inline-block;
  margin-right: 0.4rem;
}

.status-dot.connected {
  background: var(--accent);
  box-shadow: 0 0 8px var(--accent);
}

.demo-body {
  padding: 1.25rem;
}

.demo-row {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
}

.demo-row input {
  flex: 1;
  min-width: 160px;
  background: #080d16;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.55rem 0.8rem;
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
}

.demo-row input:focus {
  outline: none;
  border-color: var(--accent);
}

.btn {
  background: var(--accent);
  color: var(--bg-deep);
  border: none;
  border-radius: 8px;
  padding: 0.55rem 1rem;
  font-weight: 600;
  font-size: 0.8125rem;
  cursor: pointer;
  transition: opacity 0.2s, transform 0.15s;
  white-space: nowrap;
}

.btn:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
}

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none;
}

.message-log {
  background: #080d16;
  border: 1px solid var(--border);
  border-radius: 8px;
  height: 180px;
  overflow-y: auto;
  padding: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
}

.log-entry {
  padding: 0.25rem 0;
  border-bottom: 1px solid rgba(30, 58, 95, 0.5);
}

.log-entry .time {
  color: var(--text-muted);
  margin-right: 0.5rem;
}

.log-entry .topic {
  color: var(--info);
}

.log-entry .payload {
  color: var(--accent);
}

.log-entry.system {
  color: var(--text-muted);
  font-style: italic;
}

/* Opla dashboard */
.opla-dashboard {
  background: #080d16;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.25rem;
  margin-bottom: 1rem;
}

.opla-dashboard-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.25rem;
  flex-wrap: wrap;
}

.opla-title {
  font-weight: 700;
  font-size: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.opla-icon {
  color: var(--accent);
  font-size: 1.1rem;
}

.opla-status {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.875rem;
}

.opla-status .online { color: var(--accent); }
.opla-status .offline { color: var(--danger); }

.sensor-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 0.75rem;
  margin-bottom: 1.25rem;
}

.sensor-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1rem;
  text-align: center;
  transition: border-color 0.3s, box-shadow 0.3s;
}

.sensor-card.updated {
  border-color: var(--accent-dim);
  box-shadow: 0 0 12px var(--accent-glow);
}

.sensor-icon {
  font-size: 1.25rem;
  margin-bottom: 0.25rem;
}

.sensor-label {
  font-size: 0.7rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.35rem;
}

.sensor-value {
  font-family: var(--font-mono);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--accent);
  line-height: 1.2;
}

.sensor-value-sm {
  font-size: 1.1rem;
}

.sensor-unit {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.15rem;
}

.control-panel {
  border-top: 1px solid var(--border);
  padding-top: 1rem;
}

.control-panel h4 {
  font-size: 0.875rem;
  margin-bottom: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.control-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.control-row-actions {
  margin-top: 0.75rem;
}

.led-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 0.75rem;
  margin-bottom: 0.25rem;
}

.led-item {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.75rem;
}

.led-item-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.led-index {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text);
}

.led-picker-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.led-color-input {
  width: 44px;
  height: 32px;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: transparent;
  cursor: pointer;
}

.led-color-input:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.led-rgb-text {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--accent);
}

.led-rgb-inputs {
  display: flex;
  gap: 0.5rem;
}

.led-rgb-inputs label {
  flex: 1;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
}

.led-rgb-inputs input {
  display: block;
  width: 100%;
  margin-top: 0.2rem;
  background: #080d16;
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.35rem 0.4rem;
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
}

.led-rgb-inputs input:focus {
  outline: none;
  border-color: var(--accent);
}

.led-actions {
  display: flex;
  gap: 0.5rem;
}

.led-actions .btn {
  flex: 1;
  padding: 0.4rem 0.5rem;
  font-size: 0.75rem;
}

.btn-led-on {
  background: #22c55e;
  color: #0a0e17;
}

.led-preview {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #334155;
  border: 1px solid var(--border);
  transition: background 0.2s, box-shadow 0.2s;
  flex-shrink: 0;
}

.led-preview.active {
  background: var(--led-color, #22c55e);
  box-shadow: 0 0 10px color-mix(in srgb, var(--led-color, #22c55e) 60%, transparent);
  border-color: transparent;
}

.control-hint {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.75rem;
}

.last-update {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 1rem;
  font-family: var(--font-mono);
}

.demo-advanced {
  margin-top: 0.5rem;
}

.demo-advanced summary {
  cursor: pointer;
  font-size: 0.8125rem;
  color: var(--text-muted);
  padding: 0.5rem 0;
  user-select: none;
}

.demo-advanced summary:hover {
  color: var(--accent);
}

.demo-advanced[open] summary {
  margin-bottom: 0.75rem;
}

/* Table */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.875rem;
}

th, td {
  padding: 0.75rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

th {
  background: rgba(0, 230, 184, 0.06);
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

td {
  color: var(--text-muted);
}

/* Exercises */
.exercise-list {
  list-style: none;
  padding: 0;
  counter-reset: ex;
}

.exercise-list li {
  counter-increment: ex;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem 1rem 1rem 3.2rem;
  margin-bottom: 0.75rem;
  position: relative;
}

.exercise-list li::before {
  content: counter(ex, decimal-leading-zero);
  position: absolute;
  left: 1rem;
  top: 1rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent);
  font-weight: 700;
}

/* Footer */
footer {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 2.5rem 1.5rem;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.8125rem;
}

footer a {
  color: var(--accent);
  text-decoration: none;
}

@media (max-width: 820px) {
  .hero-grid,
  .compare-grid {
    grid-template-columns: 1fr;
  }

  header {
    flex-direction: column;
    align-items: flex-start;
  }

  nav {
    gap: 0.15rem;
    justify-content: flex-start;
  }

  .diagram-arrow {
    transform: rotate(90deg);
  }
}

/* —— Present mode —— */
.btn-present {
  margin-left: 0.35rem;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: var(--bg-deep);
  border: none;
  border-radius: 999px;
  padding: 0.4rem 0.9rem;
  font-weight: 700;
  font-size: 0.78rem;
  cursor: pointer;
}

.btn-present:hover {
  opacity: 0.92;
}

.present-chrome {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.75rem 1.25rem;
  background: rgba(6, 10, 18, 0.92);
  backdrop-filter: blur(14px);
  border-top: 1px solid var(--border);
}

.present-chrome[hidden],
.present-progress[hidden] {
  display: none !important;
}

.present-chrome-left,
.present-chrome-right,
.present-chrome-center {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.present-brand {
  font-weight: 700;
  font-size: 0.9rem;
}

.present-hint {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
}

.present-counter {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  min-width: 4.5rem;
  text-align: center;
}

.present-nav-btn {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text);
  font-size: 1.4rem;
  line-height: 1;
  cursor: pointer;
}

.present-nav-btn:hover:not(:disabled) {
  border-color: var(--accent);
  color: var(--accent);
}

.present-nav-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.present-exit {
  padding: 0.45rem 0.9rem;
}

.present-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  z-index: 201;
  background: rgba(28, 53, 88, 0.5);
}

.present-progress-bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  transition: width 0.25s ease;
}

body.present-mode {
  overflow: hidden;
}

body.present-mode > header,
body.present-mode > footer,
body.present-mode .toc {
  display: none !important;
}

body.present-mode > main {
  max-width: none;
  margin: 0;
  padding: 0;
}

body.present-mode .hero.present-slide,
body.present-mode main > section.present-slide {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 100;
  margin: 0;
  padding: 2.5rem 4vw 5.5rem;
  overflow-y: auto;
  overflow-x: hidden;
  scrollbar-width: none;
  -ms-overflow-style: none;
  background:
    radial-gradient(ellipse 70% 45% at 15% 0%, rgba(0, 230, 184, 0.1), transparent 50%),
    radial-gradient(ellipse 50% 40% at 90% 20%, rgba(91, 140, 255, 0.08), transparent 45%),
    var(--bg-deep);
  scroll-margin: 0;
}

body.present-mode .hero.present-slide::-webkit-scrollbar,
body.present-mode main > section.present-slide::-webkit-scrollbar {
  display: none;
  width: 0;
  height: 0;
}

body.present-mode .hero.present-active,
body.present-mode main > section.present-active {
  display: block;
  animation: presentFade 0.28s ease;
}

@keyframes presentFade {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

body.present-mode .hero.present-active {
  display: flex;
  align-items: center;
  justify-content: center;
}

body.present-mode .hero.present-active .hero-grid {
  max-width: 1100px;
  width: 100%;
  margin: 0 auto;
}

body.present-mode .present-active {
  font-size: 1.05rem;
}

body.present-mode .present-active h1 {
  font-size: clamp(2.4rem, 5vw, 3.6rem);
}

body.present-mode .present-active h2 {
  font-size: clamp(1.8rem, 3.5vw, 2.4rem);
  margin-bottom: 1.25rem;
}

body.present-mode .present-active h3 {
  font-size: 1.3rem;
}

body.present-mode .present-active .lead,
body.present-mode .present-active .hero-lead {
  font-size: 1.2rem;
  max-width: 52rem;
}

body.present-mode .present-active > *:not(.demo-panel) {
  max-width: 1100px;
  margin-left: auto;
  margin-right: auto;
}

body.present-mode .present-active .demo-panel,
body.present-mode .present-active .card-grid,
body.present-mode .present-active .compare-grid,
body.present-mode .present-active .diagram,
body.present-mode .present-active table,
body.present-mode .present-active .topic-tree,
body.present-mode .present-active .callout,
body.present-mode .present-active .timeline,
body.present-mode .present-active .qos-flow,
body.present-mode .present-active pre {
  max-width: 1100px;
  margin-left: auto;
  margin-right: auto;
}

body.present-mode #demo.present-active {
  padding-top: 1.5rem;
}

body.present-mode #demo.present-active .demo-block {
  max-width: 1200px;
  margin-left: auto;
  margin-right: auto;
}

body.present-mode #demo.present-active .demo-panel {
  max-width: 1200px;
}

@media (max-width: 640px) {
  .present-hint {
    display: none;
  }

  body.present-mode .hero.present-slide,
  body.present-mode main > section.present-slide {
    padding: 1.5rem 1rem 5.5rem;
  }
}

/* —— MQTT Lab / feature showcase —— */
.lab-tabs {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
  margin-bottom: 1.1rem;
  padding-bottom: 0.85rem;
  border-bottom: 1px solid var(--border);
}

.lab-tab {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-muted);
  border-radius: 999px;
  padding: 0.45rem 0.9rem;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
}

.lab-tab.active {
  color: var(--bg-deep);
  background: var(--accent);
  border-color: var(--accent);
}

.lab-pane[hidden] {
  display: none !important;
}

.lab-intro {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 1.5rem;
  max-width: 52rem;
  line-height: 1.7;
}

.feature-lab {
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
}

.demo-block {
  background: linear-gradient(165deg, rgba(17, 26, 43, 0.7), rgba(8, 13, 22, 0.95));
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 1.75rem 1.75rem 1.5rem;
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.22);
}

.demo-block-header {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 1.35rem;
  padding-bottom: 1.1rem;
  border-bottom: 1px solid var(--border);
}

.demo-block-num {
  flex-shrink: 0;
  min-width: 52px;
  height: 52px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 700;
  color: var(--bg-deep);
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  box-shadow: 0 0 24px var(--accent-glow);
}

.demo-block-kicker {
  margin: 0 0 0.25rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
}

.demo-block-header h3 {
  margin: 0;
  font-size: clamp(1.25rem, 2.4vw, 1.55rem);
  letter-spacing: -0.02em;
  color: var(--text);
}

.demo-block-grid {
  display: grid;
  grid-template-columns: 1.05fr 1fr;
  gap: 1.75rem;
  align-items: start;
}

.demo-block-copy {
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.7;
}

.demo-block-copy p {
  margin-bottom: 0.85rem;
}

.demo-block-copy ul {
  margin: 0.5rem 0 1rem 1.15rem;
}

.demo-block-copy li {
  margin-bottom: 0.4rem;
}

.demo-steps {
  margin: 1rem 0;
  padding: 0.9rem 0.9rem 0.9rem 2rem;
  background: rgba(0, 230, 184, 0.06);
  border: 1px solid rgba(0, 230, 184, 0.18);
  border-radius: 12px;
  color: var(--text-muted);
}

.demo-steps li {
  margin-bottom: 0.45rem;
}

.demo-steps li:last-child {
  margin-bottom: 0;
}

.demo-tip {
  margin: 0.75rem 0 0;
  padding: 0.75rem 0.9rem;
  border-left: 3px solid var(--accent-2);
  background: rgba(91, 140, 255, 0.08);
  border-radius: 0 10px 10px 0;
  font-size: 0.88rem;
}

.demo-tip strong {
  color: var(--text);
}

.demo-block-stage {
  background: #080d16;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 1.25rem;
  min-height: 220px;
}

.feature-result {
  margin: 1rem 0 0;
  font-size: 0.82rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  line-height: 1.5;
}

.fanout-visual {
  text-align: center;
}

.fanout-pub code {
  display: block;
  margin-top: 0.4rem;
  font-size: 0.72rem;
  color: var(--info);
}

.fanout-arrow {
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  margin: 0.55rem 0;
}

.fanout-subs {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.65rem;
}

.fanout-sub {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.85rem 0.55rem;
  font-size: 0.85rem;
  font-weight: 600;
  transition: border-color 0.2s, box-shadow 0.2s, transform 0.2s;
}

.fanout-sub small {
  display: block;
  font-weight: 400;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.62rem;
  margin-top: 0.2rem;
}

.fanout-sub.hit {
  border-color: var(--accent);
  box-shadow: 0 0 14px var(--accent-glow);
  transform: translateY(-2px);
  color: var(--accent);
}

.wildcard-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 0.6rem;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.3rem 0.7rem;
  font-size: 0.75rem;
  color: var(--text-muted);
  cursor: pointer;
}

.chip:has(input:checked) {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-glow);
}

.wildcard-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 0.6rem;
}

.wildcard-actions .btn {
  font-size: 0.72rem;
  padding: 0.35rem 0.65rem;
}

.wildcard-inbox {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  min-height: 140px;
  max-height: 220px;
  overflow-y: auto;
  padding: 0.85rem 1rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  scrollbar-width: none;
  -ms-overflow-style: none;
}

.wildcard-inbox::-webkit-scrollbar {
  display: none;
}

.wildcard-empty {
  color: var(--text-muted);
  font-style: italic;
}

.wildcard-hit {
  padding: 0.2rem 0;
  border-bottom: 1px solid rgba(30, 58, 95, 0.4);
}

.wildcard-miss {
  padding: 0.2rem 0;
  color: var(--warning);
  border-bottom: 1px solid rgba(30, 58, 95, 0.4);
}

.retain-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 0.75rem;
}

.retain-row input {
  flex: 1;
  min-width: 140px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.45rem 0.7rem;
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.retain-demo {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 0.55rem;
  align-items: center;
}

.retain-box {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.7rem;
  text-align: center;
}

.retain-box.highlight {
  border-color: rgba(0, 230, 184, 0.4);
}

.retain-label {
  display: block;
  font-size: 0.68rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.35rem;
}

.retain-box code {
  display: block;
  font-size: 0.9rem;
  color: var(--accent);
  margin-bottom: 0.25rem;
}

.retain-box small {
  color: var(--text-muted);
  font-size: 0.68rem;
}

.qos-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin-bottom: 0.7rem;
}

.qos-0-btn { background: var(--qos0); }
.qos-1-btn { background: var(--qos1); color: #111; }
.qos-2-btn { background: var(--qos2); }

.qos-results {
  display: grid;
  gap: 0.55rem;
}

.qos-result {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.75rem 0.9rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
}

.lwt-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  margin-bottom: 0.5rem;
}

.lwt-status-box {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.45rem 0.75rem;
  font-size: 0.8rem;
  min-width: 160px;
}

.bi-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  align-items: center;
}

.bi-pill {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.4rem 0.85rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

@media (max-width: 820px) {
  .feature-lab {
    gap: 1.25rem;
  }

  .demo-block {
    padding: 1.25rem;
  }

  .demo-block-grid {
    grid-template-columns: 1fr;
  }

  .retain-demo {
    grid-template-columns: 1fr;
  }

  .fanout-subs {
    grid-template-columns: 1fr;
  }
}