/* ==========================================================================
   RUTKOWSKI.TECH — INDUSTRIAL TELEMETRY, LAYER 1 SFP DATA DIODES & OT SECURITY
   Design System: Swiss Engineering Datasheet (Rev 2026.6 — Mobile & Desktop Ready)
   ========================================================================== */

:root {
  --bg-paper: #F5F4F0;
  --bg-surface: #FFFFFF;
  --bg-subtle: #EAE8E0;
  --bg-slate: #11161D;
  --bg-slate-elevated: #171F2A;
  --bg-slate-panel: #1E2938;

  --ink-primary: #11161C;
  --ink-secondary: #333E4D;
  --ink-muted: #556274;

  --cobalt: #0F4C81;
  --cobalt-hover: #0A365C;
  --cobalt-light: #38BDF8;
  --cobalt-tint: #EBF3FA;

  --signal-green: #146C43;
  --signal-led: #22C55E;
  --signal-tint: #E8F5EE;

  --danger-red: #F87171;

  --rule-light: #CFCBC0;
  --rule-strong: #11161C;
  --rule-dark: #2E3C4F;

  --font-serif: 'Source Serif 4', Georgia, 'Times New Roman', Times, serif;
  --font-sans: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'IBM Plex Mono', 'Consolas', 'Liberation Mono', 'Courier New', monospace;

  --container-max: 1240px;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  max-width: 100%;
  overflow-x: hidden;
}

body {
  background-color: var(--bg-paper);
  color: var(--ink-primary);
  font-family: var(--font-sans);
  font-size: 1.02rem;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  max-width: 100%;
  overflow-x: hidden;
}

/* Prevent Phone Numbers from Ever Breaking Into Vertical Chunks */
.js-phone {
  white-space: nowrap !important;
  display: inline-block;
}

/* Technical Top Specification Strip */
.spec-strip {
  background-color: var(--bg-slate);
  color: #E2E8F0;
  border-bottom: 1px solid var(--rule-dark);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.03em;
}

.spec-strip-inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 9px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px 16px;
}

.spec-status {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-width: 0;
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--signal-led);
  display: inline-block;
  flex-shrink: 0;
}

.spec-meta-links {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px 20px;
}

.spec-meta-links span,
.spec-meta-links a {
  white-space: nowrap;
}

.spec-meta-links a {
  color: #E2E8F0;
  text-decoration: none;
  font-weight: 500;
  transition: color 0.15s ease;
}

.spec-meta-links a:hover {
  color: var(--cobalt-light);
}

/* Primary Navigation Header (Pure Typographic Wordmark RUTKOWSKI.TECH) */
.site-header {
  background-color: var(--bg-surface);
  border-bottom: 1px solid var(--rule-light);
  position: sticky;
  top: 0;
  z-index: 50;
}

.header-inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
  min-height: 76px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
}

.brand-link {
  display: inline-flex;
  flex-direction: column;
  text-decoration: none;
  color: var(--ink-primary);
  min-width: 0;
}

.brand-name {
  font-family: var(--font-sans);
  font-size: 1.48rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  line-height: 1.05;
}

.brand-name span {
  color: var(--cobalt);
  font-weight: 500;
}

.brand-sub {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--ink-secondary);
  letter-spacing: 0.06em;
  margin-top: 4px;
  text-transform: uppercase;
  font-weight: 500;
  line-height: 1.3;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 22px;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 20px;
}

.nav-links a {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--ink-secondary);
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 6px 0;
  border-bottom: 2px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
  white-space: nowrap;
}

.nav-links a:hover {
  color: var(--cobalt);
  border-bottom-color: var(--cobalt);
}

.nav-controls {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

/* Language Switcher */
.lang-switcher {
  display: inline-flex;
  border: 1px solid var(--rule-light);
  background: var(--bg-paper);
}

.lang-btn {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 6px 10px;
  border: none;
  border-right: 1px solid var(--rule-light);
  background: transparent;
  color: var(--ink-secondary);
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease;
}

.lang-btn:last-child {
  border-right: none;
}

.lang-btn:hover {
  color: var(--ink-primary);
  background: #E5E3DC;
}

.lang-btn.active {
  background: var(--ink-primary);
  color: var(--bg-surface);
}

/* Mobile Menu Button (Hidden on Desktop, Shown on <= 1080px) */
.mobile-menu-btn {
  display: none;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 6px 11px;
  border: 1px solid var(--rule-strong);
  background: var(--bg-surface);
  color: var(--ink-primary);
  cursor: pointer;
  letter-spacing: 0.04em;
}

.mobile-menu-btn:hover,
.mobile-menu-btn[aria-expanded="true"] {
  background: var(--ink-primary);
  color: var(--bg-surface);
}

.menu-btn-icon {
  font-size: 0.92rem;
  line-height: 1;
}

/* Container & Structural Grid */
.container {
  max-width: var(--container-max);
  width: 100%;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 84px 0;
  border-bottom: 1px solid var(--rule-light);
}

.section-surface {
  background-color: var(--bg-surface);
}

.section-dark {
  background-color: var(--bg-slate);
  color: #F8FAFC;
  border-bottom-color: var(--rule-dark);
}

.section-header {
  display: grid;
  grid-template-columns: 230px 1fr;
  gap: 32px;
  margin-bottom: 48px;
  align-items: start;
}

.section-header > * {
  min-width: 0;
}

.section-index {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--cobalt);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding-top: 8px;
  border-top: 2px solid var(--cobalt);
  display: inline-block;
}

.section-dark .section-index {
  color: var(--cobalt-light);
  border-top-color: var(--cobalt-light);
}

.section-title {
  font-family: var(--font-serif);
  font-size: clamp(1.75rem, 3vw, 2.55rem);
  font-weight: 400;
  line-height: 1.2;
  letter-spacing: -0.01em;
  margin-bottom: 14px;
  overflow-wrap: break-word;
}

.section-lead {
  font-size: 1.08rem;
  line-height: 1.68;
  color: var(--ink-secondary);
  max-width: 780px;
}

.section-dark .section-lead {
  color: #CBD5E1;
}

/* Hero Section */
.hero {
  padding: 52px 0 68px;
  border-bottom: 1px solid var(--rule-light);
  background:
    linear-gradient(to right, rgba(207, 203, 192, 0.35) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(207, 203, 192, 0.35) 1px, transparent 1px);
  background-size: 48px 48px;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.08fr 0.92fr;
  gap: 40px;
  align-items: start;
}

.hero-grid > * {
  min-width: 0;
  max-width: 100%;
}

.hero-kicker {
  display: inline-block;
  max-width: 100%;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--cobalt);
  background: var(--cobalt-tint);
  border: 1px solid #B8D4EC;
  padding: 6px 14px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 18px;
  line-height: 1.4;
}

.hero h1 {
  font-family: var(--font-serif);
  font-size: clamp(1.9rem, 3.3vw, 2.95rem);
  font-weight: 400;
  line-height: 1.16;
  letter-spacing: -0.015em;
  color: var(--ink-primary);
  margin-bottom: 18px;
  overflow-wrap: break-word;
}

.hero-desc {
  font-size: 1.05rem;
  color: var(--ink-secondary);
  line-height: 1.68;
  margin-bottom: 20px;
  max-width: 64ch;
}

.telemetry-notice {
  background: var(--bg-surface);
  border-left: 4px solid var(--cobalt);
  border-top: 1px solid var(--rule-light);
  border-right: 1px solid var(--rule-light);
  border-bottom: 1px solid var(--rule-light);
  padding: 15px 18px;
  margin-bottom: 24px;
  font-size: 0.94rem;
  line-height: 1.58;
  color: var(--ink-secondary);
  max-width: 64ch;
}

.telemetry-notice strong {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--cobalt);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  display: block;
  margin-bottom: 4px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 28px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 13px 22px;
  text-decoration: none;
  border: 1px solid var(--ink-primary);
  transition: all 0.15s ease;
  cursor: pointer;
  text-align: center;
}

.btn-primary {
  background-color: var(--cobalt);
  border-color: var(--cobalt);
  color: #FFFFFF;
}

.btn-primary:hover {
  background-color: var(--cobalt-hover);
  border-color: var(--cobalt-hover);
}

.btn-secondary {
  background-color: var(--bg-surface);
  color: var(--ink-primary);
  border-color: var(--rule-strong);
}

.btn-secondary:hover {
  background-color: var(--ink-primary);
  color: var(--bg-surface);
}

.hero-metrics {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  border-top: 1px solid var(--rule-light);
  padding-top: 18px;
  gap: 16px;
}

.metric-item {
  border-left: 3px solid var(--cobalt);
  padding-left: 12px;
  min-width: 0;
}

.metric-code {
  font-family: var(--font-mono);
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--ink-primary);
  display: block;
  margin-bottom: 2px;
}

.metric-label {
  font-size: 0.82rem;
  line-height: 1.45;
  color: var(--ink-secondary);
}

/* ==========================================================================
   CRISP HTML/CSS ARCHITECTURE SCHEMATIC (Zero Clipping, Responsive on Mobile)
   ========================================================================== */
.schematic-panel {
  background-color: var(--bg-slate);
  color: #F8FAFC;
  border: 1px solid var(--rule-dark);
  padding: 20px;
  box-shadow: 0 14px 34px rgba(17, 22, 29, 0.12);
  width: 100%;
  max-width: 100%;
}

.schematic-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  border-bottom: 1px solid var(--rule-dark);
  padding-bottom: 12px;
  margin-bottom: 16px;
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: #CBD5E1;
  gap: 8px;
}

.schematic-badge {
  color: var(--signal-led);
  border: 1px solid rgba(34, 197, 94, 0.45);
  padding: 3px 9px;
  background: rgba(34, 197, 94, 0.1);
  font-weight: 600;
  white-space: nowrap;
}

.arch-diagram {
  display: flex;
  flex-direction: column;
  background:
    linear-gradient(to right, rgba(30, 41, 59, 0.45) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(30, 41, 59, 0.45) 1px, transparent 1px);
  background-size: 20px 20px;
  background-color: #131B24;
  border: 1px solid #263344;
  padding: 16px;
  width: 100%;
}

.arch-layer {
  background: #182332;
  border: 1px solid #38BDF8;
  padding: 14px 16px;
  position: relative;
  width: 100%;
}

.arch-layer-bottom {
  border-color: #475569;
}

.arch-layer-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 4px;
}

.arch-cloud-icon {
  width: 44px;
  height: 32px;
  flex-shrink: 0;
  color: var(--cobalt-light);
}

.arch-kicker {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  display: block;
  line-height: 1.4;
}

.arch-kicker-blue {
  color: var(--cobalt-light);
}

.arch-kicker-green {
  color: var(--signal-led);
  margin-bottom: 10px;
}

.arch-title {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 600;
  color: #FFFFFF;
  line-height: 1.35;
  margin-bottom: 4px;
}

.arch-sub {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: #CBD5E1;
  line-height: 1.45;
}

.arch-note {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  margin-top: 6px;
  display: block;
  line-height: 1.4;
}

.arch-note-green {
  color: var(--signal-led);
}

.arch-note-blue {
  color: var(--cobalt-light);
}

/* Upward Connector Between Layers */
.arch-connector {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 8px 4px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  text-align: center;
}

.arch-conn-line {
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.arch-conn-arrow-green,
.arch-conn-label-green {
  color: var(--signal-led);
}

.arch-conn-arrow-blue,
.arch-conn-label-blue {
  color: var(--cobalt-light);
}

/* Middle Layer 1 SFP Data Diode Box */
.arch-diode-box {
  background: #101822;
  border: 2px solid var(--signal-led);
  padding: 14px 16px;
  width: 100%;
}

.arch-sfp-module {
  background: #172230;
  border: 1px solid var(--signal-led);
  border-left: 4px solid var(--signal-led);
  padding: 9px 12px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 6px 12px;
}

.arch-sfp-tx {
  border-color: var(--cobalt-light);
  border-left-color: var(--cobalt-light);
}

.arch-sfp-sku {
  font-family: var(--font-mono);
  font-size: 0.86rem;
  font-weight: 600;
  color: #FFFFFF;
}

.arch-sfp-role {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  line-height: 1.35;
}

.arch-role-green {
  color: var(--signal-led);
}

.arch-role-blue {
  color: var(--cobalt-light);
}

/* Optical Fiber Channel Bar between TX and RX */
.arch-fiber-channel {
  margin: 8px 0;
  padding: 9px 12px;
  background: #0C1219;
  border: 1px dashed #334155;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
  align-items: center;
  font-family: var(--font-mono);
}

.arch-fiber-flow {
  min-width: 0;
}

.arch-fiber-up {
  color: var(--signal-led);
  font-size: 0.74rem;
  font-weight: 600;
  display: block;
}

.arch-fiber-specs {
  color: #CBD5E1;
  font-size: 0.68rem;
  display: block;
  margin-top: 2px;
  font-weight: 400;
  line-height: 1.4;
}

.arch-fiber-block {
  color: var(--danger-red);
  border: 1px solid rgba(248, 113, 113, 0.4);
  background: rgba(248, 113, 113, 0.08);
  padding: 4px 8px;
  font-size: 0.68rem;
  font-weight: 600;
  text-align: right;
}

.schematic-footer {
  border-top: 1px solid var(--rule-dark);
  padding-top: 12px;
  margin-top: 14px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: #CBD5E1;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}

/* Layer 1 Permanent Security Manifesto Box */
.layer1-manifesto {
  background: #162231;
  border: 1px solid var(--cobalt-light);
  border-left: 5px solid var(--signal-led);
  padding: 28px 32px;
  margin-bottom: 36px;
}

.layer1-manifesto-kicker {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--signal-led);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  display: block;
  margin-bottom: 8px;
}

.layer1-manifesto h3 {
  font-family: var(--font-serif);
  font-size: 1.6rem;
  font-weight: 400;
  color: #FFFFFF;
  margin-bottom: 10px;
  line-height: 1.25;
}

.layer1-manifesto p {
  color: #E2E8F0;
  font-size: 1rem;
  line-height: 1.7;
  max-width: 95ch;
}

/* 4 Core Pillars Grid */
.pillars-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  border-top: 1px solid var(--rule-light);
  border-left: 1px solid var(--rule-light);
}

.pillar-card {
  background-color: var(--bg-surface);
  border-right: 1px solid var(--rule-light);
  border-bottom: 1px solid var(--rule-light);
  padding: 38px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-width: 0;
}

.pillar-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 600;
  color: var(--cobalt);
  margin-bottom: 14px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--bg-subtle);
}

.pillar-card h3 {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 400;
  color: var(--ink-primary);
  margin-bottom: 12px;
  line-height: 1.25;
}

.pillar-summary {
  font-weight: 600;
  color: var(--ink-primary);
  font-size: 1rem;
  margin-bottom: 14px;
}

.pillar-body {
  color: var(--ink-secondary);
  font-size: 0.98rem;
  line-height: 1.68;
  margin-bottom: 24px;
}

.tech-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin-top: auto;
  padding-top: 16px;
  border-top: 1px dashed var(--rule-light);
}

.tech-tags li {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 500;
  background-color: var(--bg-paper);
  color: var(--ink-primary);
  border: 1px solid var(--rule-light);
  padding: 5px 10px;
}

/* Section 02: SFP Data Diode Models & Full-Width Comparison Table */
.sfp-models-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
  margin-bottom: 36px;
}

.sfp-model-box {
  background: var(--bg-slate-elevated);
  border: 1px solid var(--rule-dark);
  border-left: 4px solid var(--cobalt-light);
  padding: 28px;
  min-width: 0;
}

.sfp-model-box.rx-box {
  border-left-color: var(--signal-led);
}

.sfp-sku-badge {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--cobalt-light);
  display: block;
  margin-bottom: 8px;
}

.sfp-model-box.rx-box .sfp-sku-badge {
  color: var(--signal-led);
}

.sfp-sku-name {
  font-family: var(--font-mono);
  font-size: 1.35rem;
  font-weight: 600;
  color: #FFFFFF;
  margin-bottom: 10px;
  overflow-wrap: break-word;
}

.comparison-full-wrap {
  width: 100%;
  max-width: 100%;
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.96rem;
}

.comparison-table th,
.comparison-table td {
  border: 1px solid var(--rule-dark);
  padding: 16px 20px;
  text-align: left;
  vertical-align: top;
}

.comparison-table th {
  background-color: var(--bg-slate-panel);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: #E2E8F0;
}

.comparison-table td {
  color: #E2E8F0;
  background-color: var(--bg-slate-elevated);
}

.comparison-table td.highlight-col {
  background-color: rgba(15, 76, 129, 0.28);
  color: #FFFFFF;
  font-weight: 500;
}

.datasheet-bar {
  margin-top: 24px;
  background: var(--bg-slate-elevated);
  border: 1px solid var(--rule-dark);
  padding: 18px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.datasheet-bar-text {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: #CBD5E1;
}

/* Target Industries */
.sectors-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.sector-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--rule-light);
  padding: 34px;
  min-width: 0;
}

.sector-tag {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 600;
  color: var(--signal-green);
  background: var(--signal-tint);
  border: 1px solid #B7E1CD;
  padding: 4px 11px;
  display: inline-block;
  margin-bottom: 14px;
}

.sector-card h3 {
  font-family: var(--font-serif);
  font-size: 1.4rem;
  font-weight: 400;
  margin-bottom: 12px;
  line-height: 1.25;
}

.sector-problem {
  font-size: 0.96rem;
  color: var(--ink-secondary);
  margin-bottom: 14px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--bg-subtle);
}

.sector-solution {
  font-size: 0.96rem;
  color: var(--ink-primary);
}

.sector-solution strong {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--cobalt);
  text-transform: uppercase;
  display: block;
  margin-bottom: 4px;
}

/* Architecture Chain */
.chain-steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.chain-step {
  background: var(--bg-paper);
  border: 1px solid var(--rule-light);
  padding: 26px;
  min-width: 0;
}

.chain-step-num {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--cobalt);
  margin-bottom: 10px;
  display: block;
}

.chain-step h3 {
  font-family: var(--font-sans);
  font-size: 1.08rem;
  font-weight: 600;
  margin-bottom: 10px;
}

.chain-step p {
  font-size: 0.92rem;
  color: var(--ink-secondary);
  margin-bottom: 14px;
}

.chain-proto {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 500;
  color: var(--ink-primary);
  border-top: 1px solid var(--rule-light);
  padding-top: 10px;
}

/* FAQ Section */
.faq-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
  max-width: 980px;
}

.faq-item {
  background: var(--bg-surface);
  border: 1px solid var(--rule-light);
  padding: 26px 30px;
  min-width: 0;
}

.faq-item h3 {
  font-family: var(--font-sans);
  font-size: 1.08rem;
  font-weight: 600;
  color: var(--ink-primary);
  margin-bottom: 10px;
  line-height: 1.35;
}

.faq-item p {
  color: var(--ink-secondary);
  font-size: 0.98rem;
  line-height: 1.68;
}

/* Contact & Footer */
.contact-grid {
  display: grid;
  grid-template-columns: 1.08fr 0.92fr;
  gap: 36px;
  align-items: stretch;
}

.contact-box {
  background: var(--bg-slate-elevated);
  border: 1px solid var(--rule-dark);
  padding: 36px;
  min-width: 0;
}

.contact-row {
  padding: 15px 0;
  border-bottom: 1px solid var(--rule-dark);
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.contact-row:last-child {
  border-bottom: none;
}

.contact-label {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: #CBD5E1;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.contact-value {
  font-family: var(--font-mono);
  font-size: 1.18rem;
  color: #FFFFFF;
  overflow-wrap: break-word;
}

.contact-value a {
  color: var(--cobalt-light);
  text-decoration: none;
}

.contact-value a:hover {
  text-decoration: underline;
}

.site-footer {
  background: #0B0F14;
  color: #CBD5E1;
  border-top: 1px solid var(--rule-dark);
  padding: 32px 0;
  font-family: var(--font-mono);
  font-size: 0.78rem;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-inner a {
  color: #E2E8F0;
  text-decoration: none;
}

.footer-inner a:hover {
  color: var(--cobalt-light);
}

/* Mobile-Only Top Scroll-To-Top Button (Hidden on Desktop) */
.mobile-back-to-top {
  display: none;
}

/* ==========================================================================
   RESPONSIVE BREAKPOINTS: TABLET & MOBILE
   ========================================================================== */
@media (max-width: 1080px) {
  .spec-strip,
  .site-header,
  main,
  .hero,
  .section,
  .site-footer {
    width: 100%;
    max-width: 100vw;
    overflow-x: hidden;
  }

  .header-inner {
    flex-wrap: wrap;
    padding: 12px 20px;
    min-height: 68px;
  }

  .main-nav {
    display: contents;
  }

  .nav-controls {
    margin-left: auto;
    order: 2;
  }

  .mobile-menu-btn {
    display: inline-flex;
  }

  .nav-links {
    display: none;
    order: 3;
    width: 100%;
    flex-basis: 100%;
    flex-direction: column;
    gap: 0;
    background: var(--bg-surface);
    border-top: 1px solid var(--rule-light);
    margin-top: 10px;
    padding: 6px 0 4px;
  }

  .nav-links.is-open {
    display: flex;
  }

  .nav-links li {
    width: 100%;
    border-bottom: 1px solid var(--bg-subtle);
  }

  .nav-links li:last-child {
    border-bottom: none;
  }

  .nav-links a {
    display: block;
    width: 100%;
    padding: 12px 4px;
    font-size: 0.84rem;
    border-bottom: none;
    white-space: normal;
  }

  .hero-grid,
  .contact-grid,
  .sfp-models-grid,
  .section-header {
    display: flex;
    flex-direction: column;
    width: 100%;
    max-width: 100%;
    gap: 28px;
  }

  .section-header {
    gap: 12px;
    margin-bottom: 32px;
  }

  .chain-steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 768px) {
  .site-header {
    position: relative;
  }

  .container {
    padding: 0 16px;
  }

  /* Mobile-Only Top Scroll-To-Top Button */
  .mobile-back-to-top {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    position: fixed;
    top: 12px;
    right: 14px;
    z-index: 999;
    background: var(--cobalt);
    color: #FFFFFF;
    border: 1px solid #38BDF8;
    box-shadow: 0 6px 18px rgba(17, 22, 29, 0.38);
    padding: 8px 14px;
    font-family: var(--font-mono);
    font-size: 0.74rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(-16px);
    transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease;
  }

  .mobile-back-to-top.is-visible {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateY(0);
  }

  /* Compact Single-Line Top Bar on Mobile: Phone + Email Side by Side */
  .spec-status,
  .spec-loc {
    display: none;
  }

  .spec-strip-inner {
    padding: 8px 16px;
    justify-content: space-between;
  }

  .spec-meta-links {
    width: 100%;
    justify-content: space-between;
    gap: 8px 12px;
    font-size: 0.75rem;
  }

  .header-inner {
    padding: 12px 16px;
    gap: 10px;
  }

  .brand-name {
    font-size: 1.22rem;
  }

  .brand-sub {
    font-size: 0.56rem;
    letter-spacing: 0.03em;
    max-width: 190px;
  }

  .lang-btn {
    padding: 5px 8px;
    font-size: 0.7rem;
  }

  .mobile-menu-btn {
    padding: 5px 9px;
    font-size: 0.7rem;
  }

  .hero {
    padding: 28px 0 44px;
  }

  .hero-kicker {
    font-size: 0.68rem;
    padding: 5px 10px;
  }

  .hero h1 {
    font-size: 1.65rem;
    line-height: 1.2;
  }

  .hero-desc {
    font-size: 0.96rem;
  }

  .hero-actions {
    flex-direction: column;
    gap: 10px;
  }

  .hero-actions .btn,
  .datasheet-bar .btn {
    width: 100%;
  }

  .pillars-grid,
  .sectors-grid,
  .chain-steps,
  .hero-metrics,
  .arch-fiber-channel {
    display: flex;
    flex-direction: column;
    width: 100%;
    max-width: 100%;
  }

  .hero-metrics {
    gap: 14px;
  }

  .sectors-grid,
  .chain-steps {
    gap: 16px;
  }

  .schematic-panel {
    padding: 14px;
  }

  .arch-diagram {
    padding: 10px;
  }

  .arch-layer,
  .arch-diode-box {
    padding: 12px;
  }

  .arch-fiber-block {
    text-align: left;
    white-space: normal;
  }

  /* Responsive Full-Width Stacked Cards for Comparison Table on Mobile */
  .comparison-table,
  .comparison-table tbody,
  .comparison-table tr,
  .comparison-table td {
    display: block;
    width: 100%;
  }

  .comparison-table thead {
    display: none;
  }

  .comparison-table tr {
    margin-bottom: 16px;
    border: 1px solid var(--rule-dark);
    background: var(--bg-slate-elevated);
  }

  .comparison-table td {
    border: none;
    border-bottom: 1px solid var(--rule-dark);
    padding: 12px 14px;
    font-size: 0.9rem;
  }

  .comparison-table td:last-child {
    border-bottom: none;
  }

  .comparison-table td:nth-child(1) {
    background: var(--bg-slate-panel);
    font-family: var(--font-mono);
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--cobalt-light);
    text-transform: uppercase;
    letter-spacing: 0.04em;
  }

  .comparison-table td:nth-child(2)::before {
    content: "VLAN / FIREWALL (WARSTWY 2–7):";
    display: block;
    font-family: var(--font-mono);
    font-size: 0.68rem;
    font-weight: 600;
    color: #94A3B8;
    margin-bottom: 4px;
    letter-spacing: 0.04em;
  }

  .comparison-table td:nth-child(3)::before {
    content: "DIODA DANYCH SFP (WARSTWA 1):";
    display: block;
    font-family: var(--font-mono);
    font-size: 0.68rem;
    font-weight: 600;
    color: var(--signal-led);
    margin-bottom: 4px;
    letter-spacing: 0.04em;
  }

  .section {
    padding: 48px 0;
  }

  .pillar-card,
  .sector-card,
  .contact-box,
  .layer1-manifesto,
  .sfp-model-box,
  .faq-item,
  .chain-step {
    padding: 20px 18px;
  }

  .contact-value {
    font-size: 1.02rem;
  }
}

@media print {
  .spec-strip,
  .site-header,
  .hero-actions {
    display: none;
  }
  body {
    background: #FFFFFF;
    color: #000000;
  }
  .section {
    padding: 24px 0;
    break-inside: avoid;
  }
}