/* ==========================================================================
   FuelSense Industrial IoT — Complete Design System & Stylesheet
   Based on DESIGN.md: Modern Industrial Precision & Clean Editorial Tech
   ========================================================================== */

:root {
  /* Colors from DESIGN.md */
  --primary: #13ab9e;
  --primary-dark: #006a62;
  --primary-deep: #003833;
  --primary-fixed: #7af7e8;
  --primary-fixed-dim: #5bdacc;
  --primary-glow: rgba(19, 171, 158, 0.35);

  --secondary: #0b2f3a;
  --secondary-light: #43636f;
  --secondary-container: #c3e5f3;
  --on-secondary-container: #476773;

  --tertiary: #ffb627;
  --tertiary-dark: #cb8d00;
  --tertiary-deep: #7f5700;
  --tertiary-fixed: #ffdead;
  --tertiary-fixed-dim: #ffba3b;
  --tertiary-glow: rgba(255, 182, 39, 0.3);

  --error: #ba1a1a;
  --error-container: #ffdad6;
  --on-error-container: #93000a;

  --success: #10b981;
  --success-bg: rgba(16, 185, 129, 0.12);

  --background: #effcff;
  --surface-base: #f6faf9;
  --surface: #effcff;
  --surface-card: #ffffff;
  --surface-container-lowest: #ffffff;
  --surface-container-low: #e2f7fd;
  --surface-container: #dcf2f7;
  --surface-container-high: #d6ecf2;
  --surface-container-highest: #d1e6ec;
  --surface-mist: #d5efec;

  --on-surface: #0a1e23;
  --on-surface-variant: #3c4947;
  --outline: #6c7a77;
  --outline-variant: #bbc9c6;
  --border-hairline: rgba(11, 47, 58, 0.09);
  --border-dark-hairline: rgba(213, 239, 236, 0.15);

  /* Typography */
  --font-headline: 'Merriweather', Georgia, serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2.5rem;
  --gutter: 1.5rem;
  --max-w: 1280px;

  /* Border Radius */
  --rounded-sm: 0.25rem;
  --rounded: 0.5rem;
  --rounded-md: 0.75rem;
  --rounded-lg: 1rem;
  --rounded-xl: 1.5rem;
  --rounded-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(11, 47, 58, 0.05);
  --shadow-card: 0 4px 20px -2px rgba(11, 47, 58, 0.06), 0 2px 6px -1px rgba(11, 47, 58, 0.04);
  --shadow-hover: 0 12px 32px -4px rgba(11, 47, 58, 0.12), 0 4px 12px -2px rgba(11, 47, 58, 0.06);
  --shadow-glow: 0 0 30px rgba(19, 171, 158, 0.25);
  --shadow-dark: 0 20px 40px rgba(0, 0, 0, 0.35);

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  max-width: 100vw;
  width: 100%;
}

body {
  font-family: var(--font-body);
  background-color: var(--background);
  color: var(--on-surface);
  line-height: 1.5;
  overflow-x: hidden;
  max-width: 100vw;
  width: 100%;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: var(--secondary);
}
::-webkit-scrollbar-thumb {
  background: var(--primary-dark);
  border-radius: var(--rounded-full);
}
::-webkit-scrollbar-thumb:hover {
  background: var(--primary);
}

::selection {
  background-color: var(--primary);
  color: #ffffff;
}

/* Layout Utilities */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--gutter);
  padding-right: var(--gutter);
}

.section {
  padding: 5rem 0;
  position: relative;
}

section[id] {
  scroll-margin-top: 80px;
}

.section-dark {
  background-color: var(--secondary);
  color: #ffffff;
}

.section-alt {
  background-color: var(--surface-container-low);
  border-top: 1px solid var(--surface-container-highest);
  border-bottom: 1px solid var(--surface-container-highest);
}

/* Typography Helpers */
h1, h2, h3, h4 {
  font-family: var(--font-headline);
  font-weight: 700;
  color: inherit;
  line-height: 1.25;
}

.font-mono {
  font-family: var(--font-mono);
}

.text-primary { color: var(--primary); }
.text-primary-fixed { color: var(--primary-fixed); }
.text-tertiary { color: var(--tertiary); }
.text-error { color: var(--error); }
.text-success { color: var(--success); }
.text-muted { color: var(--on-surface-variant); }
.text-dim { color: rgba(255, 255, 255, 0.7); }

.section-header {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 3.5rem;
}

.section-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--primary);
  background: rgba(19, 171, 158, 0.12);
  padding: 0.35rem 0.85rem;
  border-radius: var(--rounded-full);
  margin-bottom: 1rem;
}

.section-tag.dark {
  color: var(--primary-fixed);
  background: rgba(19, 171, 158, 0.2);
  border: 1px solid rgba(19, 171, 158, 0.35);
}

.section-title {
  font-size: 2.25rem;
  margin-bottom: 1rem;
  letter-spacing: -0.015em;
}

.section-subtitle {
  font-size: 1.05rem;
  color: var(--on-surface-variant);
  line-height: 1.6;
}

.section-dark .section-subtitle {
  color: var(--surface-container-high);
}

/* ==========================================================================
   HEADER & NAVIGATION
   ========================================================================== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 76px;
  z-index: 1000;
  background: rgba(11, 47, 58, 0.92);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid rgba(19, 171, 158, 0.2);
  box-shadow: 0 4px 20px -2px rgba(11, 47, 58, 0.3);
  transition: all var(--transition-normal);
}

.nav-wrapper {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.logo-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: #ffffff;
}

.logo-icon-wrap {
  width: 38px;
  height: 38px;
  border-radius: var(--rounded-md);
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  display: flex;
  align-items: center;
  justify-content: center;
  color: #ffffff;
  box-shadow: 0 2px 10px rgba(19, 171, 158, 0.4);
}

.logo-text {
  font-family: var(--font-headline);
  font-size: 1.35rem;
  font-weight: 700;
  color: #ffffff;
  letter-spacing: -0.02em;
}

.logo-badge {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  text-transform: uppercase;
  color: var(--primary-fixed);
  background: rgba(19, 171, 158, 0.2);
  padding: 0.15rem 0.45rem;
  border-radius: var(--rounded-sm);
  border: 1px solid rgba(19, 171, 158, 0.4);
  margin-left: 0.25rem;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  list-style: none;
}

.nav-links a {
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--surface-container-high);
  transition: color var(--transition-fast);
  position: relative;
  padding: 0.25rem 0;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--primary-fixed);
}

.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--primary);
  border-radius: 2px;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.telemetry-indicator {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.35rem 0.75rem;
  border-radius: var(--rounded-full);
  background: rgba(19, 171, 158, 0.12);
  border: 1px solid rgba(19, 171, 158, 0.3);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--primary-fixed);
}

.telemetry-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--primary);
  box-shadow: 0 0 8px var(--primary);
  animation: pulse-dot 2s infinite ease-in-out;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.4; transform: scale(0.8); }
}

.audio-toggle-btn {
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: var(--surface-container-high);
  width: 38px;
  height: 38px;
  border-radius: var(--rounded);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

.audio-toggle-btn:hover {
  background: rgba(19, 171, 158, 0.2);
  color: var(--primary-fixed);
}

.audio-toggle-btn.active {
  background: var(--primary);
  color: #ffffff;
  border-color: var(--primary);
}

/* Mobile Menu Toggle */
.mobile-toggle {
  display: none;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: #ffffff;
  width: 38px;
  height: 38px;
  border-radius: var(--rounded);
  cursor: pointer;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

.mobile-toggle:hover {
  background: rgba(19, 171, 158, 0.2);
  color: var(--primary-fixed);
  border-color: rgba(19, 171, 158, 0.4);
}

/* ==========================================================================
   BUTTONS
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--rounded);
  font-family: var(--font-body);
  font-size: 0.875rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  border: none;
  transition: all var(--transition-normal);
  line-height: 1.25;
}

.btn-primary {
  background: var(--primary);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(19, 171, 158, 0.35);
}

.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(19, 171, 158, 0.45);
}

.btn-secondary {
  background: transparent;
  color: var(--primary-fixed);
  border: 1.5px solid rgba(122, 247, 232, 0.4);
}

.btn-secondary:hover {
  background: rgba(19, 171, 158, 0.15);
  border-color: var(--primary-fixed);
  color: #ffffff;
}

.btn-outline {
  background: transparent;
  color: var(--secondary);
  border: 1.5px solid var(--secondary);
}

.btn-outline:hover {
  background: rgba(11, 47, 58, 0.05);
}

.btn-amber {
  background: var(--tertiary);
  color: var(--secondary);
  font-weight: 700;
  box-shadow: 0 4px 14px rgba(255, 182, 39, 0.35);
}

.btn-amber:hover {
  background: var(--tertiary-fixed-dim);
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(255, 182, 39, 0.45);
}

.btn-sm {
  padding: 0.45rem 0.9rem;
  font-size: 0.8rem;
}

.btn-lg {
  padding: 0.95rem 2rem;
  font-size: 1rem;
}

/* ==========================================================================
   HERO SECTION
   ========================================================================== */
.hero-section {
  padding-top: 8.5rem;
  padding-bottom: 5.5rem;
  background: radial-gradient(circle at 80% 20%, rgba(19, 171, 158, 0.18) 0%, transparent 50%),
              radial-gradient(circle at 10% 80%, rgba(0, 56, 51, 0.6) 0%, transparent 60%),
              var(--secondary);
  position: relative;
  overflow: hidden;
}

.hero-glow-1 {
  position: absolute;
  top: -150px;
  right: -100px;
  width: 550px;
  height: 550px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(19, 171, 158, 0.25) 0%, transparent 70%);
  filter: blur(50px);
  pointer-events: none;
}

.hero-glow-2 {
  position: absolute;
  bottom: -100px;
  left: -100px;
  width: 450px;
  height: 450px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(11, 47, 58, 0.8) 0%, transparent 70%);
  filter: blur(40px);
  pointer-events: none;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 3.5rem;
  align-items: center;
  position: relative;
  z-index: 10;
}

.hero-copy {
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
}

.hero-title {
  font-size: 3.5rem;
  line-height: 1.15;
  letter-spacing: -0.025em;
  color: #ffffff;
}

.hero-title span {
  color: var(--primary-fixed);
  font-style: italic;
  font-weight: 400;
}

.hero-lead {
  font-size: 1.15rem;
  color: var(--surface-container-high);
  line-height: 1.7;
  max-width: 580px;
}

.hero-cta-group {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
}

.hero-trust-bar {
  padding-top: 1.75rem;
  border-top: 1px solid rgba(19, 171, 158, 0.2);
  display: flex;
  flex-wrap: wrap;
  gap: 1.75rem;
  color: var(--surface-container-high);
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.trust-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.trust-item .material-symbols-outlined {
  color: var(--primary);
  font-size: 1.15rem;
}

/* Hero Visual Showcase */
.hero-visual-wrapper {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 480px;
}

.hero-product-card {
  width: 100%;
  border-radius: var(--rounded-xl);
  overflow: hidden;
  background: rgba(10, 35, 43, 0.7);
  backdrop-filter: blur(12px);
  border: 1px solid rgba(19, 171, 158, 0.3);
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.6);
  position: relative;
}

.hero-product-img {
  width: 100%;
  height: 400px;
  object-fit: cover;
  display: block;
  transition: transform 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

.hero-product-card:hover .hero-product-img {
  transform: scale(1.03);
}

.hero-floating-hud {
  position: absolute;
  bottom: 1.25rem;
  left: 1.25rem;
  right: 1.25rem;
  background: rgba(8, 28, 35, 0.88);
  backdrop-filter: blur(16px);
  border: 1px solid rgba(19, 171, 158, 0.4);
  border-radius: var(--rounded-lg);
  padding: 1.25rem;
  box-shadow: 0 16px 36px rgba(0, 0, 0, 0.5);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.hud-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.hud-device-id {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--surface-container-high);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.status-badge-chip {
  padding: 0.2rem 0.6rem;
  border-radius: var(--rounded-full);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.chip-normal {
  background: rgba(16, 185, 129, 0.15);
  color: var(--success);
  border: 1px solid rgba(16, 185, 129, 0.3);
}

.chip-low {
  background: rgba(255, 182, 39, 0.18);
  color: var(--tertiary-fixed-dim);
  border: 1px solid rgba(255, 182, 39, 0.4);
}

.chip-error {
  background: rgba(186, 26, 26, 0.2);
  color: #ffdad6;
  border: 1px solid rgba(186, 26, 26, 0.4);
}

.hud-metric-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
}

.hud-metric-number {
  font-family: var(--font-headline);
  font-size: 2.25rem;
  font-weight: 700;
  color: #ffffff;
  line-height: 1;
}

.hud-metric-unit {
  font-size: 1rem;
  color: var(--surface-container-high);
  margin-left: 0.25rem;
}

.hud-bar-track {
  width: 100%;
  height: 6px;
  background: rgba(255, 255, 255, 0.12);
  border-radius: var(--rounded-full);
  overflow: hidden;
  margin-top: 0.25rem;
}

.hud-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--primary-fixed));
  border-radius: var(--rounded-full);
  transition: width 0.4s ease;
}

.hud-footnote {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--surface-container-high);
}

/* ==========================================================================
   PROBLEM VS SOLUTION (COMPARISON SECTION)
   ========================================================================== */
.comparison-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
}

.compare-card {
  background: var(--surface-card);
  border-radius: var(--rounded-xl);
  padding: 2.25rem;
  border: 1px solid var(--border-hairline);
  box-shadow: var(--shadow-card);
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.compare-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.card-negative {
  border-color: rgba(186, 26, 26, 0.25);
  background: linear-gradient(180deg, #ffffff 0%, #fff7f7 100%);
}

.card-positive {
  border: 2px solid var(--primary);
  background: linear-gradient(180deg, #ffffff 0%, #f1fcfb 100%);
  box-shadow: 0 8px 30px rgba(19, 171, 158, 0.12);
}

.compare-badge {
  position: absolute;
  top: 1.5rem;
  right: 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  padding: 0.3rem 0.65rem;
  border-radius: var(--rounded-sm);
}

.badge-negative {
  background: var(--error-container);
  color: var(--error);
}

.badge-positive {
  background: rgba(19, 171, 158, 0.15);
  color: var(--primary-dark);
}

.compare-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2rem;
}

.compare-icon-box {
  width: 48px;
  height: 48px;
  border-radius: var(--rounded-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.compare-icon-box.bad {
  background: var(--error-container);
  color: var(--error);
}

.compare-icon-box.good {
  background: rgba(19, 171, 158, 0.18);
  color: var(--primary-dark);
}

.compare-steps {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 2rem;
}

.step-row {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  padding: 0.9rem 1.1rem;
  border-radius: var(--rounded-lg);
  background: rgba(220, 242, 247, 0.35);
  border: 1px solid rgba(11, 47, 58, 0.05);
}

.step-row.step-bad {
  background: rgba(255, 218, 214, 0.35);
  border-left: 4px solid var(--error);
}

.step-row.step-warn {
  background: rgba(255, 222, 173, 0.35);
  border-left: 4px solid var(--tertiary-dark);
}

.step-row.step-success {
  background: rgba(122, 247, 232, 0.25);
  border-left: 4px solid var(--primary);
}

.step-num {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  flex-shrink: 0;
  background: var(--outline-variant);
  color: var(--on-surface-variant);
}

.step-bad .step-num {
  background: var(--error);
  color: #ffffff;
}

.step-warn .step-num {
  background: var(--tertiary-deep);
  color: #ffffff;
}

.step-success .step-num {
  background: var(--primary);
  color: #ffffff;
}

.step-text h4 {
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
}

.step-text p {
  font-size: 0.85rem;
  color: var(--on-surface-variant);
  line-height: 1.45;
}

.compare-result {
  padding-top: 1.25rem;
  border-top: 1px solid var(--border-hairline);
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.9rem;
  font-weight: 600;
}

/* ==========================================================================
   HARDWARE ARCHITECTURE SECTION
   ========================================================================== */
.arch-grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 1rem;
  margin-bottom: 3rem;
}

.arch-card {
  background: var(--surface-card);
  border-radius: var(--rounded-lg);
  padding: 1.5rem 1.25rem;
  border: 1px solid var(--border-hairline);
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 1.25rem;
  transition: all var(--transition-normal);
  cursor: pointer;
  position: relative;
}

.arch-card:hover,
.arch-card.active {
  border-color: var(--primary);
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.arch-card.active::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--primary);
  border-radius: var(--rounded-lg) var(--rounded-lg) 0 0;
}

.arch-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.arch-step-num {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--primary);
  background: var(--surface-container);
  padding: 0.2rem 0.5rem;
  border-radius: var(--rounded-sm);
}

.arch-icon {
  color: var(--primary);
  font-size: 1.75rem;
}

.arch-content h3 {
  font-size: 1.05rem;
  margin-bottom: 0.4rem;
}

.arch-content p {
  font-size: 0.8rem;
  color: var(--on-surface-variant);
  line-height: 1.45;
}

.arch-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  padding: 0.25rem 0.6rem;
  border-radius: var(--rounded-sm);
  background: var(--surface-container);
  color: var(--primary-dark);
  font-weight: 600;
  width: fit-content;
}

/* Formula Box */
.formula-box {
  background: var(--surface-card);
  border-radius: var(--rounded-xl);
  padding: 2.25rem;
  border: 1px solid rgba(19, 171, 158, 0.3);
  box-shadow: var(--shadow-card);
  display: grid;
  grid-template-columns: 1fr 1.6fr;
  gap: 2.5rem;
  align-items: center;
}

.formula-display-dark {
  background: var(--secondary);
  border-radius: var(--rounded-lg);
  padding: 1.75rem;
  color: #ffffff;
  border: 1px solid rgba(19, 171, 158, 0.25);
}

.equation-flow {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.95rem;
}

.eq-pill {
  padding: 0.4rem 0.85rem;
  border-radius: var(--rounded-sm);
  font-weight: 600;
}

.eq-net {
  background: rgba(19, 171, 158, 0.25);
  color: var(--primary-fixed);
  border: 1px solid rgba(19, 171, 158, 0.4);
}

.eq-gross {
  background: rgba(255, 255, 255, 0.1);
  color: #ffffff;
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.eq-tare {
  background: rgba(255, 182, 39, 0.25);
  color: var(--tertiary-fixed-dim);
  border: 1px solid rgba(255, 182, 39, 0.4);
}

.eq-operator {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--surface-container-high);
}

.formula-specs {
  margin-top: 1.25rem;
  padding-top: 1rem;
  border-top: 1px solid rgba(19, 171, 158, 0.2);
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--surface-container-high);
}

/* ==========================================================================
   LIVE INTERACTIVE DEMO CONSOLE (SUPERCHARGED)
   ========================================================================== */
.demo-section {
  background: radial-gradient(circle at 10% 20%, rgba(195, 229, 243, 0.5) 0%, transparent 60%),
              var(--background);
}

.demo-grid {
  display: grid;
  grid-template-columns: 1.35fr 0.85fr;
  gap: 2rem;
  align-items: flex-start;
}

.demo-console {
  background: var(--surface-card);
  border-radius: var(--rounded-xl);
  padding: 2.25rem;
  border: 1px solid var(--border-hairline);
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
}

.console-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--border-hairline);
  flex-wrap: wrap;
  gap: 1rem;
}

.console-device {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.console-device-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--rounded-md);
  background: rgba(19, 171, 158, 0.15);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
}

.console-badges {
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

/* Gauge & Cylinder Visualizer */
.telemetry-stage {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 2rem;
  align-items: center;
  padding: 1.5rem;
  background: var(--surface-container-low);
  border-radius: var(--rounded-lg);
  border: 1px solid rgba(11, 47, 58, 0.06);
}

/* Interactive Volumetric Cylinder SVG */
.cylinder-visualizer-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  position: relative;
}

.cylinder-svg {
  width: 140px;
  height: 220px;
  filter: drop-shadow(0 10px 15px rgba(11, 47, 58, 0.15));
}

.flame-simulation {
  position: absolute;
  top: -30px;
  left: calc(50% - 8px);
  display: flex;
  flex-direction: column;
  align-items: center;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.flame-particle {
  width: 16px;
  height: 28px;
  background: radial-gradient(circle at 50% 80%, #38bdf8 0%, #0284c7 35%, #f97316 70%, transparent 100%);
  border-radius: 50% 50% 20% 20%;
  animation: flicker 0.15s infinite alternate ease-in-out;
  transform-origin: bottom center;
}

@keyframes flicker {
  0% { transform: scale(1) skewX(2deg); opacity: 0.95; }
  100% { transform: scale(1.1) skewX(-2deg); opacity: 1; }
}

.telemetry-metrics-main {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.weight-callout {
  display: flex;
  flex-direction: column;
}

.weight-callout .label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  color: var(--on-surface-variant);
  letter-spacing: 0.05em;
}

.weight-big {
  font-family: var(--font-headline);
  font-size: 3.5rem;
  font-weight: 700;
  line-height: 1;
  color: var(--on-surface);
  display: flex;
  align-items: baseline;
  gap: 0.35rem;
}

.weight-big span {
  font-size: 1.5rem;
  font-family: var(--font-body);
  color: var(--on-surface-variant);
  font-weight: 400;
}

/* Horizontal Fill Progress Bar */
.fill-ratio-wrap {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.fill-ratio-header {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 600;
}

.progress-track-custom {
  width: 100%;
  height: 18px;
  background: var(--surface-container-highest);
  border-radius: var(--rounded-full);
  position: relative;
  overflow: hidden;
  box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.08);
}

.progress-fill-custom {
  height: 100%;
  width: 15%;
  background: var(--tertiary);
  border-radius: var(--rounded-full);
  transition: width 0.35s cubic-bezier(0.16, 1, 0.3, 1), background-color 0.35s ease;
}

.threshold-marker-line {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 2px;
  background: rgba(10, 30, 35, 0.4);
  z-index: 2;
}

.threshold-marker-critical {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 2px;
  background: rgba(186, 26, 26, 0.6);
  z-index: 2;
}

.progress-ticks {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--on-surface-variant);
}

/* Simulator Controls */
.controls-panel {
  background: var(--surface-container);
  border-radius: var(--rounded-lg);
  padding: 1.5rem;
  border: 1px solid rgba(11, 47, 58, 0.08);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

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

.controls-title {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--primary-dark);
}

.slider-group {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.slider-label-row {
  display: flex;
  justify-content: space-between;
  font-size: 0.9rem;
  font-weight: 500;
}

.sim-slider {
  width: 100%;
  height: 8px;
  background: var(--surface-container-highest);
  border-radius: var(--rounded-full);
  outline: none;
  -webkit-appearance: none;
  appearance: none;
  cursor: pointer;
}

.sim-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--primary);
  border: 3px solid #ffffff;
  box-shadow: 0 2px 8px rgba(19, 171, 158, 0.5);
  cursor: pointer;
  transition: transform 0.15s ease;
}

.sim-slider::-moz-range-thumb {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--primary);
  border: 3px solid #ffffff;
  box-shadow: 0 2px 8px rgba(19, 171, 158, 0.5);
  cursor: pointer;
  transition: transform 0.15s ease;
}

.sim-slider::-webkit-slider-thumb:hover,
.sim-slider::-moz-range-thumb:hover {
  transform: scale(1.15);
}

/* Quick Presets Buttons */
.presets-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.preset-btn {
  padding: 0.35rem 0.75rem;
  border-radius: var(--rounded);
  background: #ffffff;
  border: 1px solid var(--border-hairline);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--on-surface);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.preset-btn:hover,
.preset-btn.active {
  background: var(--primary);
  color: #ffffff;
  border-color: var(--primary);
}

.inputs-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.input-field-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.input-field-group label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--on-surface-variant);
}

.select-custom {
  height: 44px;
  padding: 0 0.85rem;
  border-radius: var(--rounded);
  background: #ffffff;
  border: 1px solid var(--outline-variant);
  font-family: var(--font-body);
  font-size: 0.85rem;
  color: var(--on-surface);
  outline: none;
  transition: border-color var(--transition-fast);
}

.select-custom:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(19, 171, 158, 0.25);
}

/* Stats Quad Grid */
.telemetry-quad {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
}

.quad-item {
  background: var(--surface-container-low);
  border-radius: var(--rounded-md);
  padding: 1rem;
  text-align: center;
  border: 1px solid rgba(11, 47, 58, 0.05);
}

.quad-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--on-surface-variant);
  margin-bottom: 0.25rem;
}

.quad-value {
  font-family: var(--font-headline);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--on-surface);
}

/* Side Panels */
.demo-sidebar {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.alert-mockup-card {
  background: var(--surface-card);
  border-radius: var(--rounded-xl);
  padding: 1.75rem;
  box-shadow: var(--shadow-card);
  border-left: 5px solid var(--tertiary);
  display: flex;
  flex-direction: column;
  gap: 1rem;
  transition: all var(--transition-normal);
}

.alert-top {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.alert-icon-box {
  width: 42px;
  height: 42px;
  border-radius: var(--rounded-md);
  background: rgba(255, 182, 39, 0.2);
  color: var(--tertiary-deep);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.alert-body-text {
  font-size: 0.875rem;
  color: var(--on-surface-variant);
  line-height: 1.5;
}

.alert-meta {
  padding-top: 0.75rem;
  border-top: 1px solid var(--border-hairline);
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--on-surface-variant);
}

/* ML Prediction Card */
.ml-prediction-card {
  background: var(--surface-card);
  border-radius: var(--rounded-xl);
  padding: 1.75rem;
  box-shadow: var(--shadow-card);
  border: 1px solid var(--border-hairline);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.ml-days-box {
  background: var(--surface-container-low);
  border-radius: var(--rounded-md);
  padding: 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.ml-days-big {
  font-family: var(--font-headline);
  font-size: 1.75rem;
  color: var(--primary-dark);
  font-weight: 700;
}

/* Hardware Diagnostic Card */
.diag-card {
  background: var(--secondary);
  border-radius: var(--rounded-xl);
  padding: 1.75rem;
  color: #ffffff;
  border: 1px solid rgba(19, 171, 158, 0.25);
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.diag-row {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  padding: 0.35rem 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

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

/* ==========================================================================
   ENTERPRISE & MULTI-CYLINDER MANIFOLD MANAGEMENT
   ========================================================================== */
.manifold-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 2rem;
}

.manifold-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}

.manifold-station-card {
  background: var(--surface-card);
  border-radius: var(--rounded-xl);
  padding: 1.75rem;
  border: 1px solid var(--border-hairline);
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 1.25rem;
  position: relative;
  transition: all var(--transition-normal);
}

.manifold-station-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.station-badge-top {
  position: absolute;
  top: -10px;
  right: 1.25rem;
  background: var(--tertiary-deep);
  color: #ffffff;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 700;
  padding: 0.2rem 0.55rem;
  border-radius: var(--rounded-full);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
}

.station-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.station-id {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--on-surface-variant);
  text-transform: uppercase;
}

.station-name {
  font-size: 1.1rem;
  margin-top: 0.25rem;
}

.station-level-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
}

.station-level-val {
  font-family: var(--font-headline);
  font-size: 1.75rem;
  font-weight: 700;
}

.station-level-pct {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--on-surface-variant);
}

.station-progress {
  width: 100%;
  height: 8px;
  background: var(--surface-container);
  border-radius: var(--rounded-full);
  overflow: hidden;
}

.station-progress-bar {
  height: 100%;
  border-radius: var(--rounded-full);
}

.station-footer {
  padding-top: 0.85rem;
  border-top: 1px solid var(--border-hairline);
  display: flex;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--on-surface-variant);
}

/* ==========================================================================
   FEATURES GRID (ENGINEERED CAPABILITIES)
   ========================================================================== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.75rem;
}

.feature-tile {
  background: var(--surface-card);
  border-radius: var(--rounded-xl);
  padding: 2rem;
  border: 1px solid var(--border-hairline);
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  gap: 1rem;
  transition: all var(--transition-normal);
}

.feature-tile:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
  border-color: rgba(19, 171, 158, 0.4);
}

.feature-icon-box {
  width: 52px;
  height: 52px;
  border-radius: var(--rounded-lg);
  background: rgba(19, 171, 158, 0.15);
  color: var(--primary-dark);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.75rem;
}

.feature-tile h3 {
  font-size: 1.15rem;
}

.feature-tile p {
  font-size: 0.875rem;
  color: var(--on-surface-variant);
  line-height: 1.6;
}

.feature-spec-tag {
  margin-top: auto;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--primary);
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

/* ==========================================================================
   SAVINGS & ROI CALCULATOR
   ========================================================================== */
.roi-card {
  background: var(--surface-card);
  border-radius: var(--rounded-xl);
  padding: 2.5rem;
  box-shadow: var(--shadow-card);
  border: 1px solid var(--border-hairline);
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

.roi-inputs {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.roi-results-box {
  background: linear-gradient(135deg, var(--secondary), #0e3b47);
  border-radius: var(--rounded-lg);
  padding: 2rem;
  color: #ffffff;
  border: 1px solid rgba(19, 171, 158, 0.3);
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.roi-big-stat {
  display: flex;
  flex-direction: column;
}

.roi-big-number {
  font-family: var(--font-headline);
  font-size: 2.75rem;
  color: var(--primary-fixed);
  font-weight: 700;
  line-height: 1.1;
}

.roi-breakdown-row {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--surface-container-high);
  padding: 0.4rem 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

/* ==========================================================================
   PRICING & HARDWARE KIT SECTION
   ========================================================================== */
.pricing-wrapper {
  max-width: 680px;
  margin: 0 auto;
}

.pricing-card-hero {
  background: var(--surface-card);
  border-radius: var(--rounded-xl);
  padding: 3rem 2.5rem;
  border: 2px solid var(--primary);
  box-shadow: 0 20px 45px rgba(0, 0, 0, 0.35);
  position: relative;
  color: var(--on-surface);
}

.pricing-badge-center {
  position: absolute;
  top: -15px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--primary);
  color: #ffffff;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  padding: 0.4rem 1.25rem;
  border-radius: var(--rounded-full);
  box-shadow: 0 4px 12px rgba(19, 171, 158, 0.4);
}

.price-headline {
  text-align: center;
  padding-bottom: 1.75rem;
  border-bottom: 1px solid var(--border-hairline);
  margin-bottom: 1.75rem;
}

.price-row {
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 0.5rem;
}

.price-val {
  font-family: var(--font-headline);
  font-size: 3.5rem;
  font-weight: 700;
  color: var(--on-surface);
}

.price-sub {
  font-size: 0.95rem;
  color: var(--on-surface-variant);
}

.pricing-checklist {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 2rem;
}

.checklist-item {
  display: flex;
  align-items: flex-start;
  gap: 0.85rem;
  font-size: 0.925rem;
}

.checklist-item .material-symbols-outlined {
  color: var(--primary);
  font-size: 1.25rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.pricing-actions {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

/* ==========================================================================
   TECHNICAL SPECS & ACCORDION
   ========================================================================== */
.specs-accordion {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.accordion-item {
  background: var(--surface-card);
  border-radius: var(--rounded-lg);
  border: 1px solid var(--border-hairline);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.accordion-btn {
  width: 100%;
  padding: 1.25rem 1.5rem;
  text-align: left;
  background: none;
  border: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  font-family: var(--font-headline);
  font-size: 1.05rem;
  color: var(--on-surface);
  font-weight: 700;
}

.accordion-btn .material-symbols-outlined {
  transition: transform var(--transition-fast);
  color: var(--primary);
}

.accordion-item.open .accordion-btn .material-symbols-outlined {
  transform: rotate(180deg);
}

.accordion-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease-out;
  padding: 0 1.5rem;
  font-size: 0.9rem;
  color: var(--on-surface-variant);
  line-height: 1.6;
}

.accordion-item.open .accordion-body {
  max-height: 400px;
  padding-bottom: 1.5rem;
}

/* ==========================================================================
   MODALS
   ========================================================================== */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(11, 47, 58, 0.75);
  backdrop-filter: blur(8px);
  z-index: 2000;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 2rem 1rem;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-normal);
}

.modal-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.modal-box {
  background: var(--surface-card);
  border-radius: var(--rounded-xl);
  max-width: 560px;
  width: 100%;
  padding: 2.25rem;
  box-shadow: var(--shadow-dark);
  border: 1px solid var(--border-hairline);
  position: relative;
  margin: auto;
  max-height: calc(100dvh - 3rem);
  overflow-y: auto;
  transform: scale(0.95);
  transition: transform var(--transition-normal);
}

.modal-overlay.active .modal-box {
  transform: scale(1);
}

.modal-close-btn {
  position: absolute;
  top: 1.25rem;
  right: 1.25rem;
  background: var(--surface-container);
  border: none;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--on-surface-variant);
  transition: all var(--transition-fast);
}

.modal-close-btn:hover {
  background: var(--error-container);
  color: var(--error);
}

.modal-form {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  margin-top: 1.5rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.form-group label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--on-surface);
}

.form-input {
  height: 44px;
  padding: 0 1rem;
  border-radius: var(--rounded);
  border: 1px solid var(--outline-variant);
  font-family: var(--font-body);
  font-size: 0.9rem;
  outline: none;
  transition: border-color var(--transition-fast);
}

.form-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(19, 171, 158, 0.25);
}

/* ==========================================================================
   FOOTER
   ========================================================================== */
.site-footer {
  background: var(--secondary);
  color: #ffffff;
  padding: 5rem 0 2.5rem;
  border-top: 1px solid rgba(19, 171, 158, 0.2);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1.2fr;
  gap: 3rem;
  margin-bottom: 3.5rem;
}

.footer-col h4 {
  font-family: var(--font-headline);
  font-size: 1.1rem;
  color: var(--primary-fixed-dim);
  margin-bottom: 1.25rem;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.footer-links a {
  color: var(--surface-container-high);
  text-decoration: none;
  font-size: 0.875rem;
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--primary-fixed);
}

.footer-bottom {
  padding-top: 2rem;
  border-top: 1px solid rgba(19, 171, 158, 0.15);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--surface-container-high);
  flex-wrap: wrap;
  gap: 1rem;
}

/* ==========================================================================
   MOBILE NAVIGATION DRAWER & BACKDROP OVERLAY
   ========================================================================== */
.mobile-drawer-overlay {
  position: fixed;
  inset: 0;
  background: rgba(4, 17, 22, 0.75);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  z-index: 1098;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-normal);
}

.mobile-drawer-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.mobile-drawer {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: min(320px, 86vw);
  background: #082129;
  background: linear-gradient(180deg, #0b2f3a 0%, #06191f 100%);
  border-left: 1px solid rgba(19, 171, 158, 0.3);
  box-shadow: -12px 0 36px rgba(0, 0, 0, 0.65);
  z-index: 1099;
  padding: 1.5rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  transform: translateX(100%);
  transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
}

.mobile-drawer.active {
  transform: translateX(0);
}

.mobile-drawer-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 1rem;
  border-bottom: 1px solid rgba(19, 171, 158, 0.2);
}

.mobile-drawer-close {
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: #ffffff;
  width: 36px;
  height: 36px;
  border-radius: var(--rounded);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.mobile-drawer-close:hover {
  background: rgba(186, 26, 26, 0.25);
  color: #ffdad6;
  border-color: rgba(186, 26, 26, 0.4);
}

.mobile-drawer-status {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 0.75rem;
  background: rgba(19, 171, 158, 0.12);
  border: 1px solid rgba(19, 171, 158, 0.25);
  border-radius: var(--rounded-md);
}

.mobile-drawer-nav {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.mobile-nav-link {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  padding: 0.75rem 0.85rem;
  border-radius: var(--rounded-md);
  color: var(--surface-container-high);
  text-decoration: none;
  font-size: 0.925rem;
  font-weight: 500;
  transition: all var(--transition-fast);
}

.mobile-nav-link .material-symbols-outlined {
  color: var(--primary);
  font-size: 1.25rem;
  transition: transform var(--transition-fast);
}

.mobile-nav-link:hover,
.mobile-nav-link:active {
  background: rgba(19, 171, 158, 0.15);
  color: var(--primary-fixed);
}

.mobile-nav-link:hover .material-symbols-outlined {
  transform: translateX(3px);
}

.mobile-drawer-actions {
  margin-top: auto;
  padding-top: 1.25rem;
  border-top: 1px solid rgba(19, 171, 158, 0.2);
  display: flex;
  flex-direction: column;
}

/* ==========================================================================
   RESPONSIVE DESIGN (MEDIA QUERIES)
   ========================================================================== */

/* Tablet & Smaller Desktops (<= 1024px) */
@media (max-width: 1024px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 3rem;
  }
  .arch-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .demo-grid {
    grid-template-columns: 1fr;
  }
  .manifold-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .roi-card {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Standard Tablets & Large Phones (<= 768px) */
@media (max-width: 768px) {
  :root {
    --gutter: 1.25rem;
  }

  .site-header {
    height: 70px;
  }

  .nav-wrapper {
    gap: 0.75rem;
  }

  .nav-links,
  .telemetry-indicator {
    display: none !important;
  }

  .mobile-toggle {
    display: flex;
  }

  .section {
    padding: 3.5rem 0;
  }

  .section-header {
    margin-bottom: 2.25rem;
  }

  .section-title {
    font-size: 1.95rem;
  }

  .hero-section {
    padding-top: 6.75rem;
    padding-bottom: 3.5rem;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-visual-wrapper {
    min-height: auto;
  }

  .hero-product-img {
    height: 340px;
  }

  .hero-floating-hud {
    padding: 1rem;
    bottom: 0.75rem;
    left: 0.75rem;
    right: 0.75rem;
  }

  .hud-metric-number {
    font-size: 1.85rem;
  }

  .comparison-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .compare-card {
    padding: 1.75rem 1.35rem;
  }

  .arch-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }

  .formula-box {
    grid-template-columns: 1fr;
    padding: 1.5rem 1.25rem;
    gap: 1.5rem;
  }

  .telemetry-stage {
    grid-template-columns: 1fr;
    text-align: center;
    padding: 1.5rem 1.25rem;
    gap: 1.5rem;
  }

  .cylinder-visualizer-container {
    margin: 0 auto;
  }

  .weight-big {
    justify-content: center;
    font-size: 3rem;
  }

  .telemetry-quad {
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
  }

  .demo-console {
    padding: 1.65rem 1.25rem;
    gap: 1.35rem;
  }

  .controls-panel {
    padding: 1.35rem 1.15rem;
  }

  .inputs-row {
    grid-template-columns: 1fr;
    gap: 0.85rem;
  }

  .demo-sidebar {
    gap: 1.25rem;
  }

  .alert-mockup-card,
  .ml-prediction-card,
  .diag-card {
    padding: 1.35rem 1.15rem;
  }

  .manifold-toolbar {
    margin-bottom: 1.5rem;
    gap: 1.25rem;
  }

  .manifold-grid {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }

  .features-grid {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }

  .feature-tile {
    padding: 1.65rem 1.35rem;
  }

  .roi-card {
    padding: 1.75rem 1.35rem;
    gap: 1.75rem;
  }

  .pricing-card-hero {
    padding: 2.25rem 1.5rem;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 2.25rem;
    margin-bottom: 2.5rem;
  }

  .modal-box {
    padding: 1.75rem 1.35rem;
    max-height: 90vh;
    max-height: 90dvh;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
  }
}

/* Medium Mobile Devices (<= 640px) */
@media (max-width: 640px) {
  /* Architecture cards become a clean single-column sequence on phones */
  .arch-grid {
    grid-template-columns: 1fr;
    gap: 0.85rem;
  }

  .hero-trust-bar {
    justify-content: center;
    text-align: center;
    gap: 0.75rem 1.25rem;
  }

  .formula-specs {
    flex-direction: column;
    gap: 0.5rem;
    align-items: center;
    text-align: center;
  }

  .equation-flow {
    justify-content: center;
    text-align: center;
  }

  .eq-pill {
    max-width: 100%;
    white-space: normal;
    text-align: center;
  }

  /* Commercial manifold action buttons stack neatly */
  .manifold-actions {
    flex-direction: column !important;
    width: 100%;
    gap: 0.6rem !important;
  }

  .manifold-actions .btn {
    width: 100%;
    justify-content: center;
  }

  /* Footer bottom centered alignment */
  .footer-bottom {
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: 1rem;
  }

  .footer-bottom-links {
    flex-wrap: wrap;
    justify-content: center;
    gap: 1rem !important;
  }

  /* Interactive simulator controls stacking */
  .controls-header {
    flex-direction: column;
    align-items: stretch;
    gap: 0.75rem;
    text-align: left;
  }

  #resetDemoBtn {
    width: 100%;
    justify-content: center;
  }

  .presets-group {
    flex-direction: column;
    width: 100%;
    gap: 0.45rem;
  }

  .preset-btn {
    width: 100%;
    text-align: center;
    padding: 0.55rem;
    font-size: 0.8rem;
  }

  #autoBurnBtn {
    width: 100%;
    margin-left: 0 !important;
    justify-content: center;
  }
}

/* Compact Mobile Phones (<= 480px) */
@media (max-width: 480px) {
  :root {
    --gutter: 1rem;
  }

  .site-header {
    height: 66px;
  }

  /* Hide header CTA on compact screens to give priority to logo and toggle */
  .nav-cta-btn {
    display: none !important;
  }

  .section {
    padding: 2.75rem 0;
  }

  .section-header {
    margin-bottom: 1.75rem;
  }

  .section-title {
    font-size: 1.65rem;
    line-height: 1.25;
  }

  .section-subtitle {
    font-size: 0.92rem;
    line-height: 1.55;
  }

  .hero-section {
    padding-top: 5.75rem;
    padding-bottom: 2.5rem;
  }

  .hero-title {
    font-size: 2.15rem;
    line-height: 1.15;
  }

  .hero-lead {
    font-size: 0.95rem;
    line-height: 1.6;
  }

  .hero-cta-group {
    flex-direction: column;
    width: 100%;
    gap: 0.75rem;
  }

  .hero-cta-group .btn {
    width: 100%;
    justify-content: center;
  }

  .hero-trust-bar {
    gap: 0.75rem 1rem;
    font-size: 0.75rem;
  }

  .hero-product-img {
    height: 280px;
  }

  .hero-floating-hud {
    bottom: 0.65rem;
    left: 0.65rem;
    right: 0.65rem;
    padding: 0.85rem;
    gap: 0.5rem;
  }

  .hud-metric-number {
    font-size: 1.65rem;
  }

  .hud-device-id {
    font-size: 0.68rem;
  }

  /* Comparison Cards */
  .compare-card {
    padding: 1.35rem 1rem;
  }

  .compare-badge {
    position: static;
    margin-bottom: 0.75rem;
    align-self: flex-start;
  }

  .compare-header {
    margin-bottom: 1.25rem;
    gap: 0.75rem;
  }

  .compare-icon-box {
    width: 42px;
    height: 42px;
    font-size: 1.3rem;
  }

  .step-row {
    padding: 0.75rem;
    gap: 0.65rem;
  }

  .step-text h4 {
    font-size: 0.88rem;
  }

  .step-text p {
    font-size: 0.8rem;
  }

  /* Hardware Architecture */
  .arch-card {
    padding: 1.25rem 1rem;
    gap: 0.85rem;
  }

  .formula-box {
    padding: 1.25rem 0.85rem;
  }

  .formula-display-dark {
    padding: 1rem 0.75rem;
  }

  .eq-pill {
    font-size: 0.75rem;
    padding: 0.3rem 0.5rem;
  }

  .eq-operator {
    font-size: 1.1rem;
  }

  /* Interactive Console */
  .console-top {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }

  .console-badges {
    width: 100%;
    flex-wrap: wrap;
    gap: 0.5rem;
  }

  .weight-big {
    font-size: 2.4rem;
  }

  .weight-big span {
    font-size: 1.15rem;
  }

  .fill-ratio-header {
    font-size: 0.78rem;
  }

  .progress-ticks {
    font-size: 0.65rem;
  }

  .telemetry-quad {
    gap: 0.5rem;
  }

  .quad-item {
    padding: 0.75rem 0.35rem;
  }

  .quad-value {
    font-size: 1.1rem;
  }

  .quad-label {
    font-size: 0.65rem;
  }

  /* Manifold */
  .manifold-station-card {
    padding: 1.35rem 1rem;
    gap: 1rem;
  }

  .station-name {
    font-size: 1rem;
  }

  .station-level-val {
    font-size: 1.5rem;
  }

  .station-badge-top {
    right: 0.75rem;
    font-size: 0.6rem;
    padding: 0.15rem 0.45rem;
  }

  /* ROI Calculator */
  .roi-card {
    padding: 1.35rem 1rem;
  }

  .roi-results-box {
    padding: 1.25rem 1rem;
  }

  .roi-big-number {
    font-size: 2.15rem;
  }

  .roi-breakdown-row {
    font-size: 0.78rem;
    gap: 0.5rem;
  }

  /* Pricing */
  .pricing-card-hero {
    padding: 1.75rem 1rem;
  }

  .pricing-badge-center {
    font-size: 0.68rem;
    padding: 0.3rem 0.75rem;
    top: -12px;
  }

  .price-val {
    font-size: 2.6rem;
  }

  .pricing-checklist {
    gap: 0.75rem;
    margin-bottom: 1.5rem;
  }

  .checklist-item {
    font-size: 0.825rem;
    line-height: 1.45;
    gap: 0.6rem;
  }

  .pricing-actions .btn {
    width: 100%;
    justify-content: center;
    text-align: center;
  }

  /* Accordion */
  .accordion-btn {
    padding: 1rem 0.85rem;
    font-size: 0.92rem;
    gap: 0.5rem;
  }

  .accordion-body {
    padding: 0 0.85rem;
    font-size: 0.85rem;
  }

  .accordion-item.open .accordion-body {
    max-height: 800px;
    padding-bottom: 1.25rem;
  }

  /* Modals */
  .modal-overlay {
    padding: 0.75rem;
  }

  .modal-box {
    padding: 1.35rem 1rem;
    border-radius: var(--rounded-lg);
  }

  .modal-actions {
    flex-direction: column-reverse !important;
    width: 100%;
    gap: 0.6rem !important;
  }

  .modal-actions .btn {
    width: 100%;
    justify-content: center;
  }
}

/* Extra-Narrow Screens (<= 380px) */
@media (max-width: 380px) {
  .logo-text {
    font-size: 1.1rem;
  }

  .logo-badge {
    font-size: 0.6rem;
    padding: 0.1rem 0.35rem;
  }

  .hero-title {
    font-size: 1.85rem;
  }

  .price-val {
    font-size: 2.25rem;
  }

  .roi-big-number {
    font-size: 1.95rem;
  }

  .diag-row {
    font-size: 0.72rem;
    flex-wrap: wrap;
    gap: 0.2rem;
  }

  .ml-days-big {
    font-size: 1.4rem;
  }
}