/* ==========================================================================
   Universal Unit Converter - Global Design System & Variables
   Modern Professional Metrology Tool & SaaS Aesthetic
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:ital,wght@0,400;0,500;0,600;0,700;0,800;1,400&family=JetBrains+Mono:wght@400;500;600;700&display=swap');

:root {
  /* Color Palette - Light Mode (Engineering Slate & Refined Cobalt) */
  --bg-main: #f8fafc;
  --bg-surface: #ffffff;
  --bg-surface-elevated: #ffffff;
  --bg-subtle: #f1f5f9;
  --bg-subtle-hover: #e2e8f0;
  --bg-card-glass: rgba(255, 255, 255, 0.92);
  
  --border-color: #e2e8f0;
  --border-subtle: #edf2f7;
  --border-focus: #2563eb;

  --text-primary: #0f172a;
  --text-secondary: #334155;
  --text-muted: #64748b;
  --text-inverse: #ffffff;

  --brand-primary: #2563eb;
  --brand-primary-hover: #1d4ed8;
  --brand-primary-light: rgba(37, 99, 235, 0.08);
  --brand-primary-border: rgba(37, 99, 235, 0.25);
  
  --brand-accent: #0284c7;
  --brand-accent-hover: #0369a1;

  --status-success: #10b981;
  --status-success-light: #ecfdf5;
  --status-warning: #f59e0b;
  --status-warning-light: #fffbeb;
  --status-error: #ef4444;
  --status-error-light: #fef2f2;

  /* Typography */
  --font-system: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  /* Layout & Sizing */
  --max-width: 1240px;
  --header-height: 72px;
  --radius-xs: 4px;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Shadows - Layered Elevation */
  --shadow-xs: 0 1px 2px 0 rgba(15, 23, 42, 0.04);
  --shadow-sm: 0 2px 4px 0 rgba(15, 23, 42, 0.05), 0 1px 2px 0 rgba(15, 23, 42, 0.03);
  --shadow-md: 0 6px 16px -2px rgba(15, 23, 42, 0.08), 0 2px 6px -1px rgba(15, 23, 42, 0.04);
  --shadow-lg: 0 12px 28px -4px rgba(15, 23, 42, 0.09), 0 4px 10px -2px rgba(15, 23, 42, 0.04);
  --shadow-xl: 0 24px 48px -8px rgba(15, 23, 42, 0.12), 0 8px 16px -4px rgba(15, 23, 42, 0.05);

  /* Transitions */
  --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

[data-theme="dark"] {
  /* Color Palette - Dark Mode (Obsidian & High-Tech Blue) */
  --bg-main: #090d16;
  --bg-surface: #0f172a;
  --bg-surface-elevated: #1e293b;
  --bg-subtle: #162032;
  --bg-subtle-hover: #1e2e48;
  --bg-card-glass: rgba(15, 23, 42, 0.88);

  --border-color: #1e293b;
  --border-subtle: #162032;
  --border-focus: #3b82f6;

  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #8292a7;
  --text-inverse: #090d16;

  --brand-primary: #3b82f6;
  --brand-primary-hover: #60a5fa;
  --brand-primary-light: rgba(59, 130, 246, 0.15);
  --brand-primary-border: rgba(59, 130, 246, 0.35);
  
  --brand-accent: #38bdf8;
  --brand-accent-hover: #7dd3fc;

  --status-success: #34d399;
  --status-success-light: rgba(52, 211, 153, 0.15);
  --status-warning: #fbbf24;
  --status-warning-light: rgba(251, 191, 36, 0.15);
  --status-error: #f87171;
  --status-error-light: rgba(248, 113, 113, 0.15);

  --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.4);
  --shadow-sm: 0 2px 6px 0 rgba(0, 0, 0, 0.45);
  --shadow-md: 0 8px 20px -2px rgba(0, 0, 0, 0.55);
  --shadow-lg: 0 16px 36px -4px rgba(0, 0, 0, 0.65);
  --shadow-xl: 0 28px 56px -8px rgba(0, 0, 0, 0.75);
}

/* ==========================================================================
   Base Reset & Typography
   ========================================================================== */

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

html {
  font-family: var(--font-system);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-main);
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  color: var(--text-primary);
  background-color: var(--bg-main);
  background-image: 
    radial-gradient(circle at 50% 0%, var(--brand-primary-light) 0%, transparent 60%),
    linear-gradient(to bottom, transparent, var(--bg-main));
  background-repeat: no-repeat;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

a {
  color: var(--brand-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  text-decoration: none;
  color: var(--brand-primary-hover);
}

img, svg {
  vertical-align: middle;
  max-width: 100%;
}

button, input, select, textarea {
  font: inherit;
  color: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
}

/* Focus styles for accessibility */
:focus-visible {
  outline: 2px solid var(--brand-primary);
  outline-offset: 3px;
}

/* Container */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

@media (max-width: 640px) {
  .container {
    padding-left: 1rem;
    padding-right: 1rem;
  }
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background-color: var(--bg-card-glass);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

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

.site-logo {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  font-size: 1.1875rem;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  text-decoration: none;
  flex-shrink: 0;
}

.logo-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-accent));
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.35);
}

.logo-badge {
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  padding: 0.18rem 0.45rem;
  border-radius: var(--radius-xs);
  background-color: var(--brand-primary-light);
  color: var(--brand-primary);
  border: 1px solid var(--brand-primary-border);
}

/* Header Right Navigation Container */
.header-right {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* Navigation Links */
.site-nav {
  display: flex;
  align-items: center;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.5rem 0.85rem;
  border-radius: var(--radius-md);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.nav-link:hover {
  color: var(--brand-primary);
  background-color: var(--brand-primary-light);
}

.nav-link.active {
  color: var(--brand-primary);
  background-color: var(--brand-primary-light);
  font-weight: 700;
}

/* Dropdown Menu for Converters */
.nav-item-dropdown {
  position: relative;
}

.nav-dropdown-toggle {
  cursor: pointer;
  user-select: none;
}

.nav-dropdown-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  width: 540px;
  background-color: var(--bg-surface);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl);
  padding: 1.25rem;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: translateY(8px);
  transition: all var(--transition-fast);
  z-index: 110;
}

.nav-item-dropdown:hover .nav-dropdown-menu,
.nav-item-dropdown:focus-within .nav-dropdown-menu {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: translateY(0);
}

.dropdown-header-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
  padding-left: 0.5rem;
}

.dropdown-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.4rem;
}

.dropdown-item {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.55rem 0.75rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.dropdown-item:hover {
  color: var(--brand-primary);
  background-color: var(--brand-primary-light);
  transform: translateX(2px);
}

.dropdown-item-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: var(--radius-sm);
  background-color: var(--bg-subtle);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.dropdown-item:hover .dropdown-item-icon {
  background-color: var(--brand-primary);
  color: #ffffff;
}

.dropdown-footer {
  margin-top: 0.85rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border-color);
  text-align: center;
}

.dropdown-footer-link {
  font-size: 0.8125rem;
  font-weight: 700;
  color: var(--brand-primary);
}

/* Header Actions */
.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.header-cta-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.55rem 1.15rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 700;
  color: #ffffff !important;
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-primary-hover));
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.28);
  transition: all var(--transition-fast);
  white-space: nowrap;
  min-height: 40px;
}

.header-cta-btn:hover {
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.45);
  transform: translateY(-1px);
}

.header-cta-btn:active {
  transform: scale(0.97);
}

.theme-toggle-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  min-width: 42px;
  min-height: 42px;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--border-color);
  background-color: var(--bg-surface);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  cursor: pointer;
}

.theme-toggle-btn:hover {
  background-color: var(--bg-subtle);
  color: var(--brand-primary);
  border-color: var(--brand-primary-border);
  transform: translateY(-1px);
}

.theme-toggle-btn:active {
  transform: scale(0.95);
}

.mobile-menu-btn {
  display: none;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  min-width: 42px;
  min-height: 42px;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--border-color);
  background-color: var(--bg-surface);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.mobile-menu-btn:hover {
  color: var(--brand-primary);
  border-color: var(--brand-primary-border);
  background-color: var(--bg-subtle);
}

.mobile-menu-btn:active {
  transform: scale(0.95);
}

@media (max-width: 960px) {
  .site-nav {
    display: none;
  }
  .mobile-menu-btn {
    display: inline-flex;
  }
}

@media (max-width: 520px) {
  .header-cta-btn {
    display: none;
  }
  .site-header {
    height: 62px;
  }
  :root {
    --header-height: 62px;
  }
  .site-logo {
    font-size: 1.0625rem;
  }
  .logo-icon {
    width: 32px;
    height: 32px;
  }
}

/* ==========================================================================
   Mobile Drawer & Backdrop Navigation
   ========================================================================== */

.mobile-nav-overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(15, 23, 42, 0.65);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  z-index: 999;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.mobile-nav-overlay.open {
  opacity: 1;
  visibility: visible;
}

.mobile-nav-drawer {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: 340px;
  max-width: 88vw;
  background-color: var(--bg-surface);
  border-left: 1px solid var(--border-color);
  box-shadow: var(--shadow-xl);
  z-index: 1000;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  transform: translateX(100%);
  transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

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

.mobile-drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
}

.mobile-close-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  min-width: 42px;
  min-height: 42px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background-color: var(--bg-subtle);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.mobile-close-btn:hover {
  background-color: var(--status-error-light);
  color: var(--status-error);
  border-color: var(--status-error);
}

.mobile-close-btn:active {
  transform: scale(0.92);
}

.mobile-nav-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.85rem 1rem;
  border-radius: var(--radius-lg);
  font-size: 0.9375rem;
  font-weight: 700;
  color: #ffffff !important;
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-primary-hover));
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.3);
  text-decoration: none;
  min-height: 46px;
  transition: all var(--transition-fast);
}

.mobile-nav-cta:active {
  transform: scale(0.98);
}

.mobile-nav-section {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.mobile-drawer-section-title {
  font-size: 0.6875rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  padding: 0 0.5rem 0.25rem 0.5rem;
}

.mobile-nav-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 0;
  margin: 0;
}

.mobile-converters-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.35rem;
}

.mobile-nav-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 0.75rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  text-decoration: none;
  min-height: 42px;
  transition: all var(--transition-fast);
}

.mobile-nav-link svg {
  color: var(--brand-primary);
  flex-shrink: 0;
}

.mobile-nav-link:hover,
.mobile-nav-link.active {
  background-color: var(--brand-primary-light);
  color: var(--brand-primary);
  font-weight: 700;
}

.mobile-nav-link:active {
  transform: scale(0.97);
}

.mobile-nav-footer {
  margin-top: auto;
  padding-top: 1rem;
  border-top: 1px solid var(--border-color);
}

.mobile-theme-toggle-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  width: 100%;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--border-color);
  background-color: var(--bg-subtle);
  color: var(--text-primary);
  font-size: 0.875rem;
  font-weight: 700;
  cursor: pointer;
  min-height: 44px;
  transition: all var(--transition-fast);
}

.mobile-theme-toggle-btn:hover {
  background-color: var(--brand-primary-light);
  border-color: var(--brand-primary);
  color: var(--brand-primary);
}

.mobile-theme-toggle-btn:active {
  transform: scale(0.98);
}

/* ==========================================================================
   Hero Section & Category Segmented Bar
   ========================================================================== */

.hero-section {
  padding: 3.5rem 0 2.5rem 0;
  text-align: center;
  position: relative;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1rem;
  border-radius: var(--radius-full);
  font-size: 0.8125rem;
  font-weight: 700;
  background: var(--brand-primary-light);
  color: var(--brand-primary);
  border: 1px solid var(--brand-primary-border);
  margin-bottom: 1.5rem;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.08);
}

.hero-title {
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.035em;
  color: var(--text-primary);
  margin-bottom: 1.25rem;
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
}

.hero-subtitle {
  font-size: 1.125rem;
  line-height: 1.65;
  color: var(--text-secondary);
  max-width: 720px;
  margin: 0 auto 2rem auto;
}

.hero-cta-group {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 2rem;
}

.hero-btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 700;
  color: #ffffff !important;
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-primary-hover));
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.35);
  transition: all var(--transition-fast);
}

.hero-btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(37, 99, 235, 0.45);
}

.hero-btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
  background-color: var(--bg-surface);
  border: 1.5px solid var(--border-color);
  box-shadow: var(--shadow-xs);
  transition: all var(--transition-fast);
}

.hero-btn-secondary:hover {
  border-color: var(--brand-primary);
  color: var(--brand-primary);
  background-color: var(--bg-subtle);
  transform: translateY(-2px);
}

/* Instant Search Box */
.search-container {
  position: relative;
  display: flex;
  align-items: center;
  margin: 0 auto 2.5rem auto;
  max-width: 620px;
  background-color: var(--bg-surface);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
  transition: all var(--transition-fast);
}

.search-container:focus-within {
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 4px var(--brand-primary-light), var(--shadow-lg);
}

.search-icon {
  position: absolute;
  left: 1.25rem;
  color: var(--text-muted);
  pointer-events: none;
}

.search-input {
  width: 100%;
  padding: 1rem 1.25rem 1rem 3.25rem;
  border: none;
  background: transparent;
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-primary);
  outline: none;
}

.search-input::placeholder {
  color: var(--text-muted);
}

/* Home Stats Bar */
.home-stats-bar {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.25rem;
  max-width: 960px;
  margin: 2.5rem auto 0 auto;
  padding: 1.25rem;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-sm);
}

@media (max-width: 768px) {
  .home-stats-bar {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }
}

@media (max-width: 480px) {
  .home-stats-bar {
    grid-template-columns: 1fr;
  }
}

.stat-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 0.5rem;
}

.stat-value {
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--brand-primary);
  letter-spacing: -0.02em;
  margin-bottom: 0.25rem;
}

.stat-label {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-muted);
}

.category-pills-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 0 auto 2.5rem auto;
  max-width: 1000px;
}

@media (max-width: 768px) {
  .category-pills-bar {
    justify-content: flex-start;
    flex-wrap: nowrap;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    padding: 0.25rem 0.5rem 0.75rem 0.5rem;
    scrollbar-width: none;
    margin-bottom: 1.5rem;
  }
  .category-pills-bar::-webkit-scrollbar {
    display: none;
  }
  .category-pill {
    flex-shrink: 0;
    white-space: nowrap;
    min-height: 42px;
  }
}

@media (max-width: 640px) {
  .hero-section {
    padding: 2rem 0 1.5rem 0;
  }
  .hero-title {
    font-size: clamp(1.75rem, 6.5vw, 2.35rem);
    line-height: 1.2;
    margin-bottom: 0.85rem;
  }
  .hero-subtitle {
    font-size: 0.9375rem;
    line-height: 1.55;
    margin-bottom: 1.5rem;
  }
  .hero-cta-group {
    flex-direction: column;
    width: 100%;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
  }
  .hero-btn-primary, .hero-btn-secondary {
    width: 100%;
    justify-content: center;
    min-height: 48px;
    padding: 0.85rem 1.25rem;
  }
  .search-container {
    margin-bottom: 1.5rem;
    border-radius: var(--radius-lg);
  }
  .search-input {
    font-size: 16px;
    padding: 0.85rem 1rem 0.85rem 2.85rem;
  }
  .search-icon {
    left: 1rem;
  }
  .quick-conversions-grid {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }
  .quick-conv-card {
    padding: 0.85rem 1rem;
    min-height: 52px;
  }
  .category-showcase-grid, .cat-showcase-grid, .all-tools-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
  }
  .cat-showcase-card, .tool-card {
    padding: 1.25rem;
  }
  .feature-pillars-grid, .trust-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
  }
  .pillar-box, .trust-card {
    padding: 1.25rem;
  }
  .content-section {
    padding: 2.5rem 0;
  }
  .content-section-title {
    font-size: 1.5rem;
    line-height: 1.25;
  }
  .content-section-subtitle {
    font-size: 0.9375rem;
    margin-bottom: 1.75rem;
  }
  .reference-table th, .reference-table td {
    padding: 0.65rem 0.85rem;
    font-size: 0.8125rem;
  }
  .footer-bottom {
    flex-direction: column;
    text-align: center;
    gap: 0.75rem;
  }
}

.category-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.55rem 1.1rem;
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  font-weight: 600;
  background-color: var(--bg-surface);
  border: 1.5px solid var(--border-color);
  color: var(--text-secondary);
  box-shadow: var(--shadow-xs);
  transition: all var(--transition-fast);
  cursor: pointer;
}

.category-pill:hover {
  border-color: var(--brand-primary);
  color: var(--brand-primary);
  background-color: var(--brand-primary-light);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.category-pill.active {
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-primary-hover));
  border-color: transparent;
  color: #ffffff !important;
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.35);
}

/* ==========================================================================
   Breadcrumbs
   ========================================================================== */

.breadcrumbs-nav {
  padding-top: 1.25rem;
}

.breadcrumbs-list {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  list-style: none;
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.breadcrumb-item a {
  color: var(--text-muted);
  font-weight: 500;
}

.breadcrumb-item a:hover {
  color: var(--brand-primary);
}

.breadcrumb-item.active {
  color: var(--text-primary);
  font-weight: 600;
}

.breadcrumb-separator {
  color: var(--text-muted);
  user-select: none;
}

/* ==========================================================================
   Content Sections, Methodology & Grid Architecture
   ========================================================================== */

.content-section {
  padding: 4rem 0;
}

.content-section-title {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.025em;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
  text-align: center;
}

.content-section-subtitle {
  font-size: 1.0625rem;
  color: var(--text-secondary);
  text-align: center;
  max-width: 680px;
  margin: 0 auto 2.5rem auto;
  line-height: 1.6;
}

/* Pro Tool Grid Showcases */
.category-showcase-grid, .cat-showcase-grid, .all-tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

/* Quick Conversions Grid for Homepage */
.quick-conversions-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}

.quick-conv-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem;
  background-color: var(--bg-surface);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-lg);
  text-decoration: none;
  color: var(--text-primary);
  box-shadow: var(--shadow-xs);
  transition: all var(--transition-fast);
}

.quick-conv-card:hover {
  border-color: var(--brand-primary);
  background-color: var(--brand-primary-light);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  color: var(--brand-primary);
}

.quick-conv-info {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.quick-conv-title {
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--text-primary);
}

.quick-conv-card:hover .quick-conv-title {
  color: var(--brand-primary);
}

.quick-conv-subtitle {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.quick-conv-arrow {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: var(--radius-sm);
  background-color: var(--bg-subtle);
  color: var(--text-secondary);
  font-weight: bold;
  transition: all var(--transition-fast);
}

.quick-conv-card:hover .quick-conv-arrow {
  background-color: var(--brand-primary);
  color: #ffffff;
  transform: translateX(3px);
}

.cat-showcase-card, .tool-card {
  display: flex;
  flex-direction: column;
  padding: 1.75rem;
  background-color: var(--bg-surface);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
  text-decoration: none;
  color: inherit;
  position: relative;
  overflow: hidden;
}

.cat-showcase-card::before, .tool-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--brand-primary), var(--brand-accent));
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.cat-showcase-card:hover, .tool-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--border-focus);
}

.cat-showcase-card:hover::before, .tool-card:hover::before {
  opacity: 1;
}

.cat-showcase-header {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  margin-bottom: 1rem;
}

.cat-showcase-icon, .card-icon-box {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--brand-primary-light), rgba(2, 132, 199, 0.12));
  color: var(--brand-primary);
  flex-shrink: 0;
  transition: all var(--transition-fast);
}

.cat-showcase-card:hover .cat-showcase-icon {
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-accent));
  color: #ffffff;
  transform: scale(1.05);
}

.cat-showcase-title, .card-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.01em;
  margin: 0;
}

.cat-showcase-desc, .card-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 1.25rem;
  flex-grow: 1;
}

.cat-showcase-units {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 1.25rem;
}

.unit-chip {
  display: inline-block;
  padding: 0.22rem 0.55rem;
  border-radius: var(--radius-xs);
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.cat-showcase-card:hover .unit-chip {
  border-color: var(--brand-primary-border);
  color: var(--brand-primary);
}

.cat-showcase-action {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 1rem;
  border-top: 1px solid var(--border-subtle);
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--brand-primary);
}

.cat-showcase-card:hover .cat-showcase-action span:last-child {
  transform: translateX(4px);
  transition: transform var(--transition-fast);
}

/* Feature Pillars Grid */
.feature-pillars-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.pillar-box {
  padding: 2rem;
  background-color: var(--bg-surface);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
}

.pillar-box:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-focus);
}

.pillar-box-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background-color: var(--brand-primary-light);
  color: var(--brand-primary);
  margin-bottom: 1.25rem;
}

.pillar-box-title {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.pillar-box-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.card-link-text {
  font-size: 0.8125rem;
  font-weight: 700;
  color: var(--brand-primary);
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

/* Reference Tables */
.reference-table-container {
  overflow-x: auto;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  margin: 1.5rem 0 2.5rem 0;
}

.reference-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.9375rem;
}

.reference-table th {
  background-color: var(--bg-subtle);
  padding: 0.875rem 1.25rem;
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  border-bottom: 1px solid var(--border-color);
}

.reference-table td {
  padding: 0.875rem 1.25rem;
  border-bottom: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

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

.reference-table tr:hover td {
  background-color: var(--brand-primary-light);
  color: var(--text-primary);
}

.unit-tag {
  display: inline-block;
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-xs);
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--brand-primary);
}

/* Metrology Trust Badges & Features */
.trust-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.trust-card {
  padding: 1.75rem;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  display: flex;
  gap: 1.25rem;
}

.trust-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background-color: var(--status-success-light);
  color: var(--status-success);
  flex-shrink: 0;
}

.trust-info h3 {
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.35rem;
}

.trust-info p {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* FAQ Accordion */
.faq-grid {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  max-width: 840px;
  margin: 0 auto;
}

.faq-item {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: all var(--transition-fast);
}

.faq-item[open] {
  border-color: var(--border-focus);
  box-shadow: var(--shadow-sm);
}

.faq-summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.125rem 1.25rem;
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
  cursor: pointer;
  user-select: none;
  list-style: none;
}

.faq-summary::-webkit-details-marker {
  display: none;
}

.faq-icon {
  width: 18px;
  height: 18px;
  color: var(--text-muted);
  transition: transform var(--transition-fast);
}

.faq-item[open] .faq-icon {
  transform: rotate(180deg);
  color: var(--brand-primary);
}

.faq-body {
  padding: 0 1.25rem 1.25rem 1.25rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ==========================================================================
   Footer
   ========================================================================== */

.site-footer {
  margin-top: auto;
  background-color: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  padding: 4rem 0 2.5rem 0;
}

.footer-grid, .footer-top-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: 3rem;
  margin-bottom: 3rem;
}

@media (max-width: 900px) {
  .footer-grid, .footer-top-grid {
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
  }
}

@media (max-width: 600px) {
  .footer-grid, .footer-top-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
}

.footer-brand p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-top: 0.85rem;
  max-width: 340px;
  line-height: 1.6;
}

.footer-col-title {
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
}

.footer-links, .footer-links-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.footer-links li a, .footer-link {
  font-size: 0.9rem;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  display: inline-block;
}

.footer-links li a:hover, .footer-link:hover {
  color: var(--brand-primary);
  transform: translateX(2px);
}

.footer-bottom {
  padding-top: 2rem;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.footer-standards-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-full);
  background-color: var(--status-success-light);
  color: var(--status-success);
  font-weight: 700;
  font-size: 0.75rem;
  border: 1px solid rgba(16, 185, 129, 0.25);
}

/* ==========================================================================
   Blog & Editorial System
   ========================================================================== */

.blog-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.75rem;
  margin-top: 2rem;
}

.blog-card {
  display: flex;
  flex-direction: column;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
  text-decoration: none;
  color: inherit;
}

.blog-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--border-focus);
}

.blog-card-body {
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.blog-card-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.blog-category-tag {
  display: inline-block;
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-xs);
  background-color: var(--brand-primary-light);
  color: var(--brand-primary);
  font-weight: 700;
}

.blog-card-title {
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1.4;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.blog-card-excerpt {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.blog-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 1rem;
  border-top: 1px solid var(--border-subtle);
  font-size: 0.8125rem;
  font-weight: 700;
  color: var(--brand-primary);
}

/* Featured Article Banner */
.featured-article-card {
  display: grid;
  grid-template-columns: 1fr;
  background-color: var(--bg-surface);
  border: 1.5px solid var(--brand-primary-border);
  border-radius: var(--radius-xl);
  padding: 2.25rem;
  box-shadow: var(--shadow-md);
  margin-bottom: 3rem;
  text-decoration: none;
  color: inherit;
  transition: all var(--transition-normal);
}

.featured-article-card:hover {
  border-color: var(--brand-primary);
  box-shadow: var(--shadow-xl);
  transform: translateY(-2px);
}

/* Article Page Layout */
.article-container {
  max-width: 820px;
  margin: 0 auto 4rem auto;
}

.article-header {
  margin-bottom: 2.5rem;
  padding-bottom: 1.75rem;
  border-bottom: 1px solid var(--border-color);
}

.article-title {
  font-size: clamp(2rem, 3.5vw, 2.75rem);
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -0.025em;
  color: var(--text-primary);
  margin: 1rem 0 1.25rem 0;
}

.article-meta-bar {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 1.25rem;
  font-size: 0.875rem;
  color: var(--text-muted);
}

.article-meta-item {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

/* Table of Contents */
.toc-box {
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin-bottom: 2.5rem;
}

.toc-title {
  font-size: 0.9375rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-primary);
  margin-bottom: 0.85rem;
}

.toc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.toc-link {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.toc-link:hover {
  color: var(--brand-primary);
}

/* Article Prose Typography */
.article-prose {
  font-size: 1.0625rem;
  line-height: 1.75;
  color: var(--text-secondary);
}

.article-prose p {
  margin-bottom: 1.5rem;
}

.article-prose h2 {
  font-size: 1.625rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin: 2.5rem 0 1rem 0;
  padding-top: 0.5rem;
}

.article-prose h3 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 1.75rem 0 0.75rem 0;
}

.article-prose ul, .article-prose ol {
  margin-bottom: 1.5rem;
  padding-left: 1.5rem;
}

.article-prose li {
  margin-bottom: 0.5rem;
}

.article-callout {
  background-color: var(--brand-primary-light);
  border-left: 4px solid var(--brand-primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: 1.25rem 1.5rem;
  margin: 2rem 0;
  font-size: 1rem;
}

.article-callout strong {
  color: var(--brand-primary);
}

/* Article Tool CTA Banner */
.article-converter-cta {
  background: linear-gradient(135deg, var(--bg-surface) 0%, var(--bg-subtle) 100%);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 2rem;
  margin: 3rem 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1.5rem;
  box-shadow: var(--shadow-md);
}

.article-cta-info h3 {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 0.35rem;
}

.article-cta-info p {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  margin: 0;
}

.cta-button {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  font-size: 0.9375rem;
  font-weight: 700;
  color: #ffffff !important;
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-primary-hover));
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
  transition: all var(--transition-fast);
}

.cta-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(37, 99, 235, 0.4);
}