/* ============================================
   WorldCalculator.net — Global Stylesheet
   ============================================ */

:root {
  /* Color system */
  --primary-50: #eef6ff;
  --primary-100: #d9eaff;
  --primary-200: #bcd9ff;
  --primary-300: #8ec1ff;
  --primary-400: #599dff;
  --primary-500: #2f7bf6;
  --primary-600: #1a5fe0;
  --primary-700: #154bb8;
  --primary-800: #163e94;
  --primary-900: #163674;

  --accent-50: #e8fbf4;
  --accent-100: #c6f5e6;
  --accent-200: #91e8d0;
  --accent-300: #5bd6b6;
  --accent-400: #2cc39d;
  --accent-500: #15a887;
  --accent-600: #0d8a70;
  --accent-700: #0a6f5a;

  --success-500: #16a34a;
  --warning-500: #f59e0b;
  --error-500: #dc2626;

  --neutral-0: #ffffff;
  --neutral-50: #f8fafc;
  --neutral-100: #f1f5f9;
  --neutral-200: #e2e8f0;
  --neutral-300: #cbd5e1;
  --neutral-400: #94a3b8;
  --neutral-500: #64748b;
  --neutral-600: #475569;
  --neutral-700: #334155;
  --neutral-800: #1e293b;
  --neutral-900: #0f172a;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Courier New', monospace;

  /* Spacing (8px system) */
  --space-1: 0.5rem;
  --space-2: 1rem;
  --space-3: 1.5rem;
  --space-4: 2rem;
  --space-5: 2.5rem;
  --space-6: 3rem;
  --space-7: 3.5rem;
  --space-8: 4rem;

  /* Radii */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -2px rgba(0,0,0,0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -4px rgba(0,0,0,0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.05);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;

  /* Layout */
  --max-width: 1200px;
  --header-height: 64px;
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.5;
  color: var(--neutral-800);
  background: var(--neutral-50);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

h1, h2, h3, h4, h5, h6 {
  line-height: 1.2;
  font-weight: 700;
  color: var(--neutral-900);
}

h1 { font-size: clamp(1.75rem, 4vw, 2.5rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); }
h3 { font-size: clamp(1.25rem, 2.5vw, 1.5rem); }

p { line-height: 1.6; }

a {
  color: var(--primary-600);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover { color: var(--primary-800); }

img { max-width: 100%; height: auto; }

/* ==================== Header ==================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--neutral-0);
  border-bottom: 1px solid var(--neutral-200);
  box-shadow: var(--shadow-sm);
  height: var(--header-height);
  display: flex;
  align-items: center;
}

.header-inner {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-2);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--neutral-900);
  letter-spacing: -0.02em;
}

.logo:hover { color: var(--neutral-900); }

.logo-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--primary-500), var(--accent-500));
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.1rem;
  font-weight: 800;
  flex-shrink: 0;
}

.logo-text { white-space: nowrap; }

.main-nav {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  list-style: none;
}

.nav-links a {
  color: var(--neutral-700);
  font-weight: 500;
  font-size: 0.95rem;
  padding: var(--space-1) 0;
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary-500);
  transition: width var(--transition-base);
}

.nav-links a:hover::after,
.nav-links a.active::after { width: 100%; }

.nav-search {
  position: relative;
}

.nav-search input {
  width: 200px;
  padding: 0.5rem 1rem 0.5rem 2.25rem;
  border: 1px solid var(--neutral-300);
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  background: var(--neutral-50);
  transition: all var(--transition-fast);
}

.nav-search input:focus {
  outline: none;
  border-color: var(--primary-400);
  box-shadow: 0 0 0 3px var(--primary-50);
  background: var(--neutral-0);
  width: 260px;
}

.nav-search::before {
  content: '🔍';
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  font-size: 0.85rem;
  opacity: 0.5;
  pointer-events: none;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--neutral-700);
  padding: var(--space-1);
}

/* Search results dropdown */
.search-results {
  position: absolute;
  top: calc(100% + 4px);
  left: 0;
  right: 0;
  background: var(--neutral-0);
  border: 1px solid var(--neutral-200);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  max-height: 300px;
  overflow-y: auto;
  display: none;
  z-index: 200;
}

.search-results.active { display: block; }

.search-results a {
  display: block;
  padding: 0.625rem 1rem;
  color: var(--neutral-700);
  font-size: 0.9rem;
  border-bottom: 1px solid var(--neutral-100);
}

.search-results a:hover {
  background: var(--primary-50);
  color: var(--primary-700);
}

.search-results .no-results {
  padding: 1rem;
  color: var(--neutral-500);
  text-align: center;
  font-size: 0.875rem;
}

/* ==================== Main ==================== */
main {
  flex: 1;
  width: 100%;
}

.page-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-4) var(--space-2);
}

/* ==================== Hero ==================== */
.hero {
  text-align: center;
  padding: var(--space-7) var(--space-2);
  background: linear-gradient(180deg, var(--primary-50) 0%, var(--neutral-50) 100%);
}

.hero h1 {
  margin-bottom: var(--space-2);
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
}

.hero p {
  font-size: 1.125rem;
  color: var(--neutral-600);
  max-width: 600px;
  margin: 0 auto var(--space-4);
}

.hero-search {
  max-width: 500px;
  margin: 0 auto;
  position: relative;
}

.hero-search input {
  width: 100%;
  padding: 0.875rem 1.25rem 0.875rem 2.75rem;
  border: 1px solid var(--neutral-300);
  border-radius: var(--radius-full);
  font-size: 1rem;
  background: var(--neutral-0);
  box-shadow: var(--shadow-md);
  transition: all var(--transition-fast);
}

.hero-search input:focus {
  outline: none;
  border-color: var(--primary-400);
  box-shadow: 0 0 0 4px var(--primary-50);
}

.hero-search::before {
  content: '🔍';
  position: absolute;
  left: 1.25rem;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1.1rem;
  opacity: 0.5;
}

/* ==================== Category Grid ==================== */
.section-title {
  text-align: center;
  margin-bottom: var(--space-4);
}

.section-title h2 {
  margin-bottom: var(--space-1);
}

.section-title p {
  color: var(--neutral-500);
  font-size: 1rem;
}

.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-3);
  margin-bottom: var(--space-6);
}

.category-card {
  background: var(--neutral-0);
  border: 1px solid var(--neutral-200);
  border-radius: var(--radius-lg);
  padding: var(--space-3);
  transition: all var(--transition-base);
  text-decoration: none;
  color: inherit;
  display: block;
}

.category-card:hover {
  border-color: var(--primary-300);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.category-card .cat-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: var(--space-2);
  background: var(--primary-50);
}

.category-card h3 {
  font-size: 1.125rem;
  margin-bottom: 0.25rem;
}

.category-card p {
  font-size: 0.875rem;
  color: var(--neutral-500);
}

.category-card .cat-count {
  display: inline-block;
  margin-top: var(--space-1);
  font-size: 0.8rem;
  color: var(--primary-600);
  font-weight: 600;
}

/* ==================== Calculator Grid ==================== */
.calc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: var(--space-2);
  margin-bottom: var(--space-6);
}

.calc-card {
  background: var(--neutral-0);
  border: 1px solid var(--neutral-200);
  border-radius: var(--radius-md);
  padding: var(--space-2) var(--space-3);
  transition: all var(--transition-base);
  text-decoration: none;
  color: inherit;
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.calc-card:hover {
  border-color: var(--primary-300);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.calc-card .calc-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background: var(--accent-50);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  flex-shrink: 0;
}

.calc-card h3 {
  font-size: 1rem;
  margin-bottom: 0.125rem;
}

.calc-card p {
  font-size: 0.8rem;
  color: var(--neutral-500);
}

/* ==================== Calculator Page ==================== */
.calc-page {
  max-width: 800px;
  margin: 0 auto;
  padding: var(--space-4) var(--space-2);
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--neutral-500);
  margin-bottom: var(--space-2);
  flex-wrap: wrap;
}

.breadcrumb a { color: var(--neutral-500); }
.breadcrumb a:hover { color: var(--primary-600); }
.breadcrumb .separator { opacity: 0.5; }

.calc-header {
  margin-bottom: var(--space-3);
}

.calc-header h1 {
  font-size: clamp(1.75rem, 3.5vw, 2.25rem);
  margin-bottom: var(--space-1);
}

.calc-header .calc-subtitle {
  color: var(--neutral-500);
  font-size: 1.05rem;
}

/* Calculator widget */
.calc-widget {
  background: var(--neutral-0);
  border: 1px solid var(--neutral-200);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
  box-shadow: var(--shadow-md);
  margin-bottom: var(--space-4);
}

.calc-form {
  display: grid;
  gap: var(--space-2);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-2);
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

.form-group label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--neutral-700);
}

.form-group input,
.form-group select {
  padding: 0.625rem 0.875rem;
  border: 1px solid var(--neutral-300);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-family: var(--font-sans);
  background: var(--neutral-50);
  transition: all var(--transition-fast);
  color: var(--neutral-900);
  width: 100%;
}

.form-group input:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--primary-400);
  box-shadow: 0 0 0 3px var(--primary-50);
  background: var(--neutral-0);
}

.form-group .hint {
  font-size: 0.8rem;
  color: var(--neutral-400);
}

.input-with-prefix {
  position: relative;
}

.input-with-prefix .prefix {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--neutral-500);
  font-size: 0.95rem;
  pointer-events: none;
}

.input-with-prefix input {
  padding-left: 1.75rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--font-sans);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.btn-primary {
  background: var(--primary-600);
  color: white;
}

.btn-primary:hover {
  background: var(--primary-700);
  color: white;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-primary:active { transform: translateY(0); }

.btn-secondary {
  background: var(--neutral-100);
  color: var(--neutral-700);
}

.btn-secondary:hover {
  background: var(--neutral-200);
}

.btn-row {
  display: flex;
  gap: var(--space-1);
  margin-top: var(--space-1);
}

/* Results */
.calc-results {
  margin-top: var(--space-3);
  padding: var(--space-3);
  background: var(--primary-50);
  border-radius: var(--radius-md);
  border: 1px solid var(--primary-100);
  display: none;
}

.calc-results.active {
  display: block;
  animation: fadeIn 0.3s ease;
}

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

.result-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-2);
  margin-bottom: var(--space-2);
}

.result-card {
  background: var(--neutral-0);
  border-radius: var(--radius-md);
  padding: var(--space-2);
  text-align: center;
}

.result-card .label {
  font-size: 0.8rem;
  color: var(--neutral-500);
  margin-bottom: 0.25rem;
}

.result-card .value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-700);
}

.result-card .value.accent { color: var(--accent-600); }

.result-highlight {
  text-align: center;
  padding: var(--space-2);
  font-size: 1.1rem;
}

.result-highlight .big-number {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--primary-600);
  display: block;
  margin-bottom: 0.25rem;
}

.result-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: var(--space-2);
  font-size: 0.875rem;
}

.result-table th {
  text-align: left;
  padding: 0.5rem;
  background: var(--neutral-100);
  color: var(--neutral-700);
  font-weight: 600;
  border-bottom: 2px solid var(--neutral-200);
}

.result-table td {
  padding: 0.5rem;
  border-bottom: 1px solid var(--neutral-100);
}

.result-table tr:hover { background: var(--neutral-50); }

.result-table .total-row {
  font-weight: 700;
  background: var(--neutral-50);
}

.error-msg {
  color: var(--error-500);
  font-size: 0.875rem;
  margin-top: 0.5rem;
  display: none;
}

.error-msg.active { display: block; }

/* Content section (SEO) */
.content-section {
  max-width: 800px;
  margin: var(--space-4) auto;
  padding: 0 var(--space-2);
}

.content-section h2 {
  margin-top: var(--space-3);
  margin-bottom: var(--space-1);
}

.content-section h3 {
  margin-top: var(--space-2);
  margin-bottom: var(--space-1);
}

.content-section p {
  margin-bottom: var(--space-2);
  color: var(--neutral-700);
}

.content-section ul, .content-section ol {
  margin-left: 1.5rem;
  margin-bottom: var(--space-2);
}

.content-section li {
  margin-bottom: 0.5rem;
  color: var(--neutral-700);
}

/* FAQ */
.faq-section {
  max-width: 800px;
  margin: var(--space-4) auto;
  padding: 0 var(--space-2);
}

.faq-item {
  border: 1px solid var(--neutral-200);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-1);
  overflow: hidden;
}

.faq-question {
  padding: var(--space-2) var(--space-3);
  background: var(--neutral-0);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
  color: var(--neutral-800);
  transition: background var(--transition-fast);
}

.faq-question:hover { background: var(--neutral-50); }

.faq-question .toggle {
  font-size: 1.25rem;
  color: var(--primary-500);
  transition: transform var(--transition-base);
}

.faq-item.open .faq-question .toggle { transform: rotate(45deg); }

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow);
  padding: 0 var(--space-3);
}

.faq-item.open .faq-answer {
  max-height: 500px;
  padding: var(--space-2) var(--space-3);
}

.faq-answer p {
  color: var(--neutral-600);
  font-size: 0.95rem;
}

/* ==================== Ad Slots ==================== */
.ad-slot {
  width: 100%;
  min-height: 90px;
  margin: var(--space-3) auto;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--neutral-100);
  border: 1px dashed var(--neutral-300);
  border-radius: var(--radius-md);
  color: var(--neutral-400);
  font-size: 0.8rem;
  text-align: center;
  max-width: 728px;
}

.ad-slot.ad-leaderboard { min-height: 90px; }
.ad-slot.ad-rectangle { min-height: 250px; max-width: 336px; }
.ad-slot.ad-responsive { min-height: 120px; }

/* ==================== Related ==================== */
.related-calcs {
  max-width: 800px;
  margin: var(--space-4) auto;
  padding: 0 var(--space-2);
}

.related-calcs h2 {
  font-size: 1.25rem;
  margin-bottom: var(--space-2);
}

.related-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.related-list a {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  background: var(--neutral-0);
  border: 1px solid var(--neutral-200);
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  color: var(--neutral-700);
  transition: all var(--transition-fast);
}

.related-list a:hover {
  border-color: var(--primary-300);
  color: var(--primary-700);
  background: var(--primary-50);
}

/* ==================== Footer ==================== */
.site-footer {
  background: var(--neutral-900);
  color: var(--neutral-400);
  padding: var(--space-5) var(--space-2) var(--space-3);
  margin-top: var(--space-6);
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-4);
}

.footer-brand .logo { color: white; margin-bottom: var(--space-1); }
.footer-brand p { font-size: 0.875rem; max-width: 300px; }

.footer-col h4 {
  color: white;
  font-size: 0.95rem;
  margin-bottom: var(--space-1);
}

.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 0.5rem; }
.footer-col a { color: var(--neutral-400); font-size: 0.875rem; }
.footer-col a:hover { color: var(--primary-300); }

.footer-bottom {
  max-width: var(--max-width);
  margin: var(--space-4) auto 0;
  padding-top: var(--space-3);
  border-top: 1px solid var(--neutral-800);
  text-align: center;
  font-size: 0.8rem;
  color: var(--neutral-500);
}

/* ==================== Responsive ==================== */
@media (max-width: 900px) {
  .footer-inner { grid-template-columns: 1fr 1fr; }
  .footer-brand { grid-column: 1 / -1; }
}

@media (max-width: 768px) {
  .nav-toggle { display: block; }
  .nav-links {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--neutral-0);
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-2);
    border-bottom: 1px solid var(--neutral-200);
    box-shadow: var(--shadow-lg);
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: all var(--transition-base);
    gap: 0;
  }
  .nav-links.active {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }
  .nav-links li {
    width: 100%;
  }
  .nav-links a {
    display: block;
    padding: 0.75rem 0;
    width: 100%;
    border-bottom: 1px solid var(--neutral-100);
  }
  .nav-links a::after { display: none; }
  .nav-search { display: none; }
  .form-row { grid-template-columns: 1fr; }
  .hero { padding: var(--space-5) var(--space-2); }
}

@media (max-width: 480px) {
  .footer-inner { grid-template-columns: 1fr; }
  .page-container { padding: var(--space-3) var(--space-1); }
  .calc-widget { padding: var(--space-2); }
  .result-card .value { font-size: 1.25rem; }
  .result-highlight .big-number { font-size: 2rem; }
}

/* ==================== Copy/Share Buttons ==================== */
.copy-share-row {
  display: flex;
  gap: 0.5rem;
  justify-content: center;
  margin-top: 1rem;
}

.btn-copy, .btn-share {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  padding: 0.5rem 1rem;
  border: 1px solid var(--neutral-300);
  border-radius: var(--radius-sm);
  background: var(--neutral-0);
  color: var(--neutral-700);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-copy:hover, .btn-share:hover {
  border-color: var(--primary-400);
  background: var(--primary-50);
  color: var(--primary-700);
}

/* ==================== Skip Link (Accessibility) ==================== */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--primary-600);
  color: white;
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
  font-weight: 600;
  z-index: 10000;
  border-radius: 0 0 var(--radius-sm) 0;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 0;
  color: white;
}

/* ==================== Search Overlay ==================== */
.search-overlay {
  position: fixed;
  inset: 0;
  z-index: 9999;
  display: none;
  align-items: flex-start;
  justify-content: center;
  padding-top: 10vh;
}

.search-overlay.active {
  display: flex;
}

.search-overlay-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
  animation: fadeIn 0.2s ease;
}

.search-overlay-panel {
  position: relative;
  width: 90%;
  max-width: 600px;
  background: var(--neutral-0);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  overflow: hidden;
  animation: slideDown 0.2s ease;
}

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-20px); }
  to { opacity: 1; transform: translateY(0); }
}

.search-overlay-panel input {
  width: 100%;
  padding: 1.25rem 1.5rem;
  border: none;
  border-bottom: 1px solid var(--neutral-200);
  font-size: 1.1rem;
  font-family: var(--font-sans);
  background: var(--neutral-0);
  color: var(--neutral-900);
  outline: none;
}

.search-overlay-results {
  max-height: 400px;
  overflow-y: auto;
  padding: 0.5rem;
}

.search-overlay-item {
  display: flex;
  align-items: flex-start;
  gap: 0.625rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  color: var(--neutral-700);
  text-decoration: none;
  transition: background var(--transition-fast);
  cursor: pointer;
}

.search-overlay-item:hover,
.search-overlay-item.selected {
  background: var(--primary-50);
  color: var(--primary-700);
}

.search-overlay-item span {
  font-weight: 600;
  font-size: 0.95rem;
  display: block;
}

.search-overlay-item small {
  font-size: 0.8rem;
  color: var(--neutral-400);
  display: block;
  margin-top: 0.125rem;
}

.search-group {
  margin-bottom: 0.5rem;
}

.search-group-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--neutral-400);
  padding: 0.5rem 1rem 0.25rem;
}

.search-overlay-empty {
  padding: 2rem;
  text-align: center;
  color: var(--neutral-500);
  font-size: 0.95rem;
}

.search-overlay-footer {
  display: flex;
  gap: 1.5rem;
  padding: 0.75rem 1.5rem;
  border-top: 1px solid var(--neutral-100);
  font-size: 0.75rem;
  color: var(--neutral-400);
}

.search-overlay-footer kbd {
  display: inline-block;
  padding: 0.125rem 0.375rem;
  border: 1px solid var(--neutral-300);
  border-radius: 4px;
  font-size: 0.7rem;
  font-family: var(--font-mono);
  background: var(--neutral-50);
  margin-right: 0.25rem;
}

/* ==================== Back to Top ==================== */
.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-full);
  background: var(--primary-600);
  color: white;
  border: none;
  font-size: 1.25rem;
  cursor: pointer;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all var(--transition-base);
  z-index: 9000;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--primary-700);
  transform: translateY(-2px);
}

.back-to-top:active {
  transform: translateY(0);
}

/* ==================== Loading Spinner ==================== */
.calc-loading {
  display: none;
  text-align: center;
  padding: 1.5rem;
}

.calc-loading.active {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.625rem;
}

.spinner {
  width: 20px;
  height: 20px;
  border: 3px solid var(--neutral-200);
  border-top-color: var(--primary-500);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.calc-loading .loading-text {
  font-size: 0.9rem;
  color: var(--neutral-500);
}

/* ==================== Related Tools Auto ==================== */
.related-calcs .related-list:empty {
  display: none;
}