/* ==========================================================================
   OmniCalc & SmartTools Hub - Core Design System & Global Styles
   Modern, Ultra-Fast, Mobile-First, Light/Dark Mode
   ========================================================================== */

:root {
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;

  /* Light Theme Palette */
  --bg-primary: #f8fafc;
  --bg-surface: #ffffff;
  --bg-surface-elevated: #ffffff;
  --bg-muted: #f1f5f9;
  --border-color: #e2e8f0;
  --border-focus: #3b82f6;

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --text-accent: #2563eb;

  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-light: #eff6ff;
  --primary-glow: rgba(37, 99, 235, 0.15);

  --success: #10b981;
  --success-light: #ecfdf5;
  --warning: #f59e0b;
  --warning-light: #fffbeb;

  --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --card-shadow-hover: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.04);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg-primary: #0b0f19;
  --bg-surface: #111827;
  --bg-surface-elevated: #1f2937;
  --bg-muted: #1e293b;
  --border-color: #2e384d;
  --border-focus: #60a5fa;

  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #64748b;
  --text-accent: #60a5fa;

  --primary: #3b82f6;
  --primary-hover: #60a5fa;
  --primary-light: rgba(59, 130, 246, 0.12);
  --primary-glow: rgba(59, 130, 246, 0.25);

  --success: #34d399;
  --success-light: rgba(52, 211, 153, 0.12);
  --warning: #fbbf24;
  --warning-light: rgba(251, 191, 36, 0.12);

  --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
  --card-shadow-hover: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 8px 10px -6px rgba(0, 0, 0, 0.3);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.3s ease, color 0.3s ease;
}

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

a:hover {
  color: var(--primary-hover);
}

/* Header & Navigation */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background-color: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  transition: var(--transition);
}

[data-theme="dark"] .site-header {
  background-color: rgba(17, 24, 39, 0.85);
}

.header-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0.85rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.brand-icon {
  width: 34px;
  height: 34px;
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  font-size: 1.1rem;
  font-weight: 900;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.35);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  list-style: none;
}

.nav-link {
  color: var(--text-secondary);
  font-weight: 600;
  font-size: 0.95rem;
  padding: 0.35rem 0.65rem;
  border-radius: var(--radius-sm);
}

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

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.theme-toggle-btn {
  background: var(--bg-muted);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  width: 38px;
  height: 38px;
  border-radius: var(--radius-full);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  transition: var(--transition);
}

.theme-toggle-btn:hover {
  border-color: var(--primary);
  transform: scale(1.05);
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
  width: 100%;
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 3rem 1rem 2rem;
  max-width: 850px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.35rem 0.85rem;
  background: var(--primary-light);
  color: var(--primary);
  font-size: 0.85rem;
  font-weight: 700;
  border-radius: var(--radius-full);
  margin-bottom: 1.25rem;
  border: 1px solid rgba(37, 99, 235, 0.2);
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.hero-title .highlight {
  background: linear-gradient(135deg, #2563eb, #9333ea);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 2rem;
}

/* Search Bar */
.search-wrapper {
  position: relative;
  max-width: 650px;
  margin: 0 auto 2rem;
}

.search-input {
  width: 100%;
  padding: 1rem 1.25rem 1rem 3.25rem;
  font-size: 1.05rem;
  font-family: inherit;
  background: var(--bg-surface);
  color: var(--text-primary);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--card-shadow);
  transition: var(--transition);
}

.search-input:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 4px var(--primary-glow);
}

.search-icon {
  position: absolute;
  left: 1.25rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  font-size: 1.25rem;
  pointer-events: none;
}

/* Category Filter Tabs */
.category-tabs {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2.5rem;
}

.category-tab {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.55rem 1.1rem;
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.category-tab:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.category-tab.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
  box-shadow: 0 4px 12px var(--primary-glow);
}

/* Tools Grid */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3.5rem;
}

.tool-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  transition: var(--transition);
  position: relative;
  text-decoration: none;
  color: inherit;
  overflow: hidden;
}

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

.tool-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.tool-card-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.tool-badge {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.25rem 0.6rem;
  border-radius: var(--radius-full);
  background: var(--bg-muted);
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.tool-badge.featured {
  background: var(--warning-light);
  color: var(--warning);
}

.tool-card-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  line-height: 1.3;
}

.tool-card-desc {
  color: var(--text-secondary);
  font-size: 0.92rem;
  line-height: 1.5;
  margin-bottom: 1.25rem;
  flex-grow: 1;
}

.tool-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 1rem;
  border-top: 1px solid var(--border-color);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary);
}

.tool-card-footer span {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  transition: transform 0.2s ease;
}

.tool-card:hover .tool-card-footer span {
  transform: translateX(4px);
}

/* Advertisement Slots */
.ad-slot {
  margin: 2rem auto;
  padding: 1.25rem;
  background: var(--bg-surface);
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-md);
  text-align: center;
  max-width: 970px;
  overflow: hidden;
}

.ad-slot-label {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.ad-slot-placeholder {
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-muted);
  border-radius: var(--radius-sm);
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 600;
}

/* Breadcrumb */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  list-style: none;
}

.breadcrumb a {
  color: var(--text-secondary);
}

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

.breadcrumb-separator {
  color: var(--text-muted);
}

/* Calculator Layout */
.calc-header {
  margin-bottom: 2rem;
}

.calc-title {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: 900;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.calc-description {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 780px;
}

.calc-layout {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 2rem;
  margin-bottom: 3rem;
  align-items: start;
}

@media (max-width: 900px) {
  .calc-layout {
    grid-template-columns: 1fr;
  }
}

.calc-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--card-shadow);
}

.calc-card-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* Form Controls */
.form-group {
  margin-bottom: 1.35rem;
}

.form-label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.form-label-desc {
  font-size: 0.8rem;
  font-weight: normal;
  color: var(--text-muted);
}

.input-with-affix {
  position: relative;
  display: flex;
  align-items: center;
}

.input-affix {
  position: absolute;
  font-weight: 700;
  color: var(--text-muted);
  font-size: 0.95rem;
  pointer-events: none;
}

.input-affix.prefix {
  left: 1rem;
}

.input-affix.suffix {
  right: 1rem;
}

.form-input {
  width: 100%;
  padding: 0.85rem 1rem;
  font-size: 1.05rem;
  font-family: inherit;
  font-weight: 600;
  background: var(--bg-primary);
  color: var(--text-primary);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  transition: var(--transition);
}

.form-input.has-prefix {
  padding-left: 2.25rem;
}

.form-input.has-suffix {
  padding-right: 2.5rem;
}

.form-input:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--primary-glow);
}

.form-range {
  width: 100%;
  margin-top: 0.5rem;
  height: 6px;
  background: var(--bg-muted);
  border-radius: var(--radius-full);
  outline: none;
  -webkit-appearance: none;
  appearance: none;
}

.form-range::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--primary);
  cursor: pointer;
  box-shadow: 0 2px 6px rgba(37, 99, 235, 0.4);
  transition: transform 0.1s ease;
}

.form-range::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}

.pill-group {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.pill-btn {
  flex: 1;
  min-width: 80px;
  padding: 0.65rem 0.85rem;
  background: var(--bg-primary);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  text-align: center;
  transition: var(--transition);
}

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

.pill-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
  box-shadow: 0 4px 10px var(--primary-glow);
}

/* Results Display */
.result-hero {
  background: linear-gradient(135deg, rgba(37, 99, 235, 0.08), rgba(147, 51, 234, 0.08));
  border: 1.5px solid rgba(37, 99, 235, 0.2);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  text-align: center;
  margin-bottom: 1.5rem;
}

.result-hero-label {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

.result-hero-value {
  font-size: 2.75rem;
  font-weight: 900;
  color: var(--primary);
  letter-spacing: -0.02em;
  line-height: 1.1;
  margin-bottom: 0.5rem;
}

.result-hero-sub {
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* Results Table */
.results-table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 1.5rem;
}

.results-table tr {
  border-bottom: 1px solid var(--border-color);
}

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

.results-table td {
  padding: 0.85rem 0.5rem;
  font-size: 0.95rem;
}

.results-table td:first-child {
  color: var(--text-secondary);
}

.results-table td:last-child {
  text-align: right;
  font-weight: 700;
  color: var(--text-primary);
  font-family: var(--font-mono);
}

/* Action Buttons */
.btn-action-group {
  display: flex;
  gap: 0.75rem;
}

.btn-primary {
  flex: 1;
  padding: 0.85rem 1.25rem;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-weight: 700;
  font-size: 0.95rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  transition: var(--transition);
  box-shadow: 0 4px 12px var(--primary-glow);
}

.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-2px);
}

.btn-secondary {
  padding: 0.85rem 1.25rem;
  background: var(--bg-muted);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  transition: var(--transition);
}

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

/* Editorial / SEO Content */
.article-section {
  max-width: 900px;
  margin: 3rem auto;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  box-shadow: var(--card-shadow);
}

.article-section h2 {
  font-size: 1.65rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-top: 2rem;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.article-section h2:first-child {
  margin-top: 0;
}

.article-section h3 {
  font-size: 1.25rem;
  font-weight: 700;
  margin-top: 1.5rem;
  margin-bottom: 0.75rem;
  color: var(--text-primary);
}

.article-section p {
  color: var(--text-secondary);
  margin-bottom: 1.25rem;
  font-size: 1.02rem;
  line-height: 1.7;
}

.article-section ul, .article-section ol {
  margin-left: 1.5rem;
  margin-bottom: 1.5rem;
  color: var(--text-secondary);
}

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

.formula-box {
  background: var(--bg-muted);
  border-left: 4px solid var(--primary);
  padding: 1.25rem 1.5rem;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 1.5rem 0;
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--text-primary);
}

/* FAQ Accordion */
.faq-list {
  margin-top: 1.5rem;
}

.faq-item {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: 0.75rem;
  overflow: hidden;
  transition: var(--transition);
}

.faq-question {
  width: 100%;
  padding: 1.15rem 1.35rem;
  text-align: left;
  background: var(--bg-surface);
  border: none;
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.faq-icon {
  font-size: 1.2rem;
  transition: transform 0.25s ease;
  color: var(--primary);
}

.faq-item.active .faq-icon {
  transform: rotate(180deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s cubic-bezier(0, 1, 0, 1);
  background: var(--bg-primary);
}

.faq-answer-inner {
  padding: 1.25rem 1.35rem;
  color: var(--text-secondary);
  font-size: 0.98rem;
  line-height: 1.6;
}

.faq-item.active .faq-answer {
  max-height: 1000px;
  transition: max-height 0.4s ease-in-out;
}

/* Toast Notification */
.toast {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background: #0f172a;
  color: white;
  padding: 0.85rem 1.5rem;
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: 0.9rem;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
  display: flex;
  align-items: center;
  gap: 0.65rem;
  transform: translateY(100px);
  opacity: 0;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  z-index: 100;
}

.toast.show {
  transform: translateY(0);
  opacity: 1;
}

/* Footer */
.site-footer {
  margin-top: auto;
  background: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  padding: 3rem 1.5rem 2rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: 2.5rem;
  margin-bottom: 2.5rem;
}

@media (max-width: 768px) {
  .footer-container {
    grid-template-columns: 1fr;
  }
}

.footer-brand p {
  margin-top: 0.75rem;
  font-size: 0.92rem;
  line-height: 1.6;
  max-width: 320px;
}

.footer-col h4 {
  color: var(--text-primary);
  font-weight: 700;
  margin-bottom: 1rem;
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 0.65rem;
}

.footer-links a {
  color: var(--text-secondary);
}

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

.footer-bottom {
  max-width: 1200px;
  margin: 0 auto;
  padding-top: 2rem;
  border-top: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}


/* ==========================================================================
   OmniCalc Hub - Multi-Country & Unit Switching System Styles
   US Customary + UK / Canada / Australia / Metric SI Standards
   ========================================================================== */

/* 1. Header Country & Unit Selector */
.unit-country-selector {
  position: relative;
  display: inline-block;
  margin-right: 0.75rem;
}

.unit-selector-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background-color: var(--bg-muted);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  padding: 0.45rem 0.85rem;
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  user-select: none;
}

.unit-selector-btn:hover {
  background-color: var(--bg-surface-elevated);
  border-color: var(--primary);
  color: var(--primary);
  box-shadow: 0 0 10px var(--primary-glow);
}

.unit-selector-btn .arrow-down {
  font-size: 0.7rem;
  color: var(--text-muted);
  transition: transform 0.2s ease;
}

.unit-dropdown-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  width: 320px;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--card-shadow-hover);
  padding: 0.5rem;
  z-index: 1000;
  display: none;
  animation: dropdownFadeIn 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

.unit-dropdown-menu.show {
  display: block;
}

@keyframes dropdownFadeIn {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}

.unit-dropdown-header {
  padding: 0.5rem 0.75rem 0.4rem;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 0.35rem;
}

.unit-dropdown-header span {
  display: block;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-primary);
}

.unit-dropdown-header small {
  display: block;
  font-size: 0.72rem;
  color: var(--text-muted);
}

.unit-options-list {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.unit-opt {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.6rem 0.75rem;
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  text-align: left;
  cursor: pointer;
  width: 100%;
  transition: var(--transition);
}

.unit-opt:hover {
  background-color: var(--primary-light);
}

.unit-opt.active {
  background-color: var(--primary-light);
  border: 1px solid rgba(59, 130, 246, 0.2);
}

.unit-opt .opt-flag {
  font-size: 1.3rem;
  line-height: 1;
}

.unit-opt .opt-info {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.unit-opt .opt-info strong {
  font-size: 0.88rem;
  color: var(--text-primary);
}

.unit-opt .opt-info small {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.unit-opt .opt-check {
  font-weight: bold;
  color: var(--primary);
  font-size: 0.95rem;
}

/* 2. Tool Inline Unit Toggle Bar */
.tool-unit-toggle-bar {
  background: var(--bg-muted);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.75rem 1rem;
  margin-bottom: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.unit-toggle-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.unit-toggle-title {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-primary);
}

.unit-toggle-pills {
  display: inline-flex;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-full);
  padding: 3px;
  gap: 4px;
}

.unit-pill {
  padding: 0.4rem 0.85rem;
  font-size: 0.8rem;
  font-weight: 600;
  background: transparent;
  color: var(--text-secondary);
  border: none;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: var(--transition);
}

.unit-pill:hover {
  color: var(--text-primary);
}

.unit-pill.active {
  background: var(--primary);
  color: #ffffff;
  box-shadow: 0 2px 6px rgba(37, 99, 235, 0.35);
}

.unit-toggle-note {
  font-size: 0.75rem;
  color: var(--text-muted);
  line-height: 1.4;
}

/* 3. US Trust & Standards Bar (Homepage) */
.us-trust-bar {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1rem;
  margin: 1.5rem 0 2rem 0;
  padding: 1rem 1.25rem;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--card-shadow);
}

.trust-item {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.trust-item .trust-icon {
  font-size: 1.25rem;
}

/* 4. Floating Quick Unit Converter FAB & Modal */
.quick-converter-fab {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 999;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--primary);
  color: #ffffff;
  border: none;
  border-radius: var(--radius-full);
  padding: 0.75rem 1.2rem;
  font-size: 0.9rem;
  font-weight: 700;
  box-shadow: 0 8px 20px rgba(37, 99, 235, 0.35);
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.quick-converter-fab:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 25px rgba(37, 99, 235, 0.45);
}

.quick-converter-modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  z-index: 10000;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  opacity: 0;
  transition: opacity 0.2s ease;
}

.quick-converter-modal.show {
  display: flex;
  opacity: 1;
}

.converter-dialog {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 480px;
  box-shadow: var(--card-shadow-hover);
  overflow: hidden;
  animation: dialogScale 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes dialogScale {
  from { transform: scale(0.92); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

.converter-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.2rem 1.5rem;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-surface-elevated);
}

.converter-title-wrap {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.converter-title-wrap h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0;
}

.converter-close-btn {
  background: transparent;
  border: none;
  font-size: 1.5rem;
  line-height: 1;
  color: var(--text-muted);
  cursor: pointer;
}

.converter-close-btn:hover {
  color: var(--text-primary);
}

.converter-tabs {
  display: flex;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-muted);
  overflow-x: auto;
}

.c-tab {
  flex: 1;
  padding: 0.75rem 0.5rem;
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  white-space: nowrap;
  transition: var(--transition);
}

.c-tab:hover {
  color: var(--text-primary);
}

.c-tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  background: var(--bg-surface);
}

.converter-body {
  padding: 1.5rem;
}

.c-panel {
  display: none;
  flex-direction: column;
  gap: 0.75rem;
}

.c-panel.active {
  display: flex;
}

.c-row {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.c-row label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.c-row input {
  padding: 0.65rem 0.85rem;
  border: 1px solid var(--border-color);
  background: var(--bg-primary);
  color: var(--text-primary);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-family: var(--font-mono);
}

.c-row input:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--primary-glow);
}

.c-divider {
  text-align: center;
  font-weight: bold;
  color: var(--primary);
  font-size: 1.2rem;
  margin: -0.25rem 0;
}

.c-sep {
  border: none;
  border-top: 1px dashed var(--border-color);
  margin: 0.5rem 0;
}

.converter-footer {
  padding: 0.75rem 1.5rem;
  background: var(--bg-muted);
  border-top: 1px solid var(--border-color);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.78rem;
}

@media (max-width: 600px) {
  .quick-converter-fab {
    bottom: 16px;
    right: 16px;
    padding: 0.6rem 0.9rem;
    font-size: 0.82rem;
  }
  .unit-dropdown-menu {
    width: 290px;
    right: -20px;
  }
}