/* ==========================================================================
   CalculatorTools.online - Production SaaS CSS Architecture
   Color Palette:
     Primary: #2563EB | Secondary: #0F172A | Background: #F8FAFC | Cards: #FFFFFF
     Text: #1E293B | Muted: #64748B | Borders: #E2E8F0 | Success: #16A34A
   ========================================================================== */

:root {
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  /* Color Palette (Light Mode Default) */
  --primary: #2563EB;
  --primary-hover: #1D4ED8;
  --primary-light: #EFF6FF;
  --primary-focus: rgba(37, 99, 235, 0.25);
  --secondary: #0F172A;
  --secondary-hover: #1E293B;
  --bg-body: #F8FAFC;
  --bg-card: #FFFFFF;
  --bg-card-subtle: #F1F5F9;
  --text-main: #1E293B;
  --text-muted: #64748B;
  --border: #E2E8F0;
  --border-focus: #2563EB;
  --success: #16A34A;
  --success-light: #DCFCE7;
  --warning: #D97706;
  --warning-light: #FEF3C7;
  --danger: #DC2626;

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 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, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.04);

  /* Dimensions & Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-xl: 20px;
  --container-max: 1200px;
  --header-height: 72px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
}

/* Dark Mode Overrides */
html.dark {
  --primary: #3B82F6;
  --primary-hover: #60A5FA;
  --primary-light: rgba(59, 130, 246, 0.15);
  --primary-focus: rgba(59, 130, 246, 0.35);
  --secondary: #F8FAFC;
  --secondary-hover: #E2E8F0;
  --bg-body: #0B0F19;
  --bg-card: #151D2E;
  --bg-card-subtle: #1E293B;
  --text-main: #F1F5F9;
  --text-muted: #94A3B8;
  --border: #243046;
  --border-focus: #3B82F6;
  --success: #22C55E;
  --success-light: rgba(34, 197, 94, 0.15);
  --warning: #F59E0B;
  --warning-light: rgba(245, 158, 11, 0.15);
  --danger: #EF4444;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -4px rgba(0, 0, 0, 0.4);
}

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

html {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-main);
  background-color: var(--bg-body);
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  width: 100%;
}

body {
  min-height: 100vh;
  width: 100%;
  overflow-x: hidden;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-body);
  color: var(--text-main);
}

img, svg {
  display: block;
  max-width: 100%;
}

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

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

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

ul, ol {
  list-style: none;
}

/* Skip link */
.skip-to-content {
  position: absolute;
  top: -9999px;
  left: 1rem;
  background: var(--primary);
  color: #fff;
  padding: 0.5rem 1rem;
  z-index: 9999;
  border-radius: var(--radius-sm);
  font-weight: 600;
}
.skip-to-content:focus {
  top: 1rem;
}

/* Utility Helpers */
.hidden { display: none !important; }
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

.icon {
  width: 1.25rem;
  height: 1.25rem;
  flex-shrink: 0;
}

/* Header & Sticky Nav */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(248, 250, 252, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

html.dark .site-header {
  background-color: rgba(11, 15, 25, 0.92);
}

.header-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 1.5rem;
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: var(--text-main);
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.025em;
}

.brand-logo:hover {
  color: var(--text-main);
}

.logo-icon-box {
  width: 2.25rem;
  height: 2.25rem;
  background: linear-gradient(135deg, var(--primary), #1D4ED8);
  color: #FFFFFF;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.25);
}

.logo-icon-box .icon {
  width: 1.35rem;
  height: 1.35rem;
}

.logo-highlight {
  color: var(--primary);
}

.desktop-nav {
  display: flex;
  align-items: center;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.5rem 0.85rem;
  border-radius: var(--radius-md);
  color: var(--text-muted);
  font-weight: 500;
  font-size: 0.95rem;
  transition: all var(--transition-fast);
}

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

.nav-link .icon {
  width: 1rem;
  height: 1rem;
}

/* Nav Dropdown */
.nav-dropdown-wrapper {
  position: relative;
}

.dropdown-menu {
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 240px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 0.5rem;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: all var(--transition-fast);
  z-index: 105;
}

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

.dropdown-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.65rem 0.85rem;
  border-radius: var(--radius-md);
  color: var(--text-main);
  font-size: 0.9rem;
  font-weight: 500;
  transition: background var(--transition-fast), color var(--transition-fast);
}

.dropdown-item:hover {
  background-color: var(--primary-light);
  color: var(--primary);
}

.dropdown-icon {
  color: var(--primary);
  display: flex;
  align-items: center;
}

/* Header Action Buttons */
.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.search-trigger-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 0.45rem 0.85rem;
  border-radius: var(--radius-lg);
  font-size: 0.9rem;
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
}

.search-trigger-btn:hover {
  border-color: var(--primary);
  color: var(--text-main);
}

.kbd-pill {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.1rem 0.35rem;
  color: var(--text-muted);
}

.theme-toggle-btn, .mobile-menu-btn {
  width: 2.75rem;
  height: 2.75rem;
  min-width: 44px;
  min-height: 44px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  background-color: var(--bg-card);
  color: var(--text-main);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.theme-toggle-btn:hover, .mobile-menu-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.dark-show { display: none; }
.light-show { display: block; }
html.dark .dark-show { display: block; }
html.dark .light-show { display: none; }

.mobile-menu-btn {
  display: none;
}

/* Mobile Drawer */
.mobile-drawer {
  border-top: 1px solid var(--border);
  background-color: var(--bg-card);
  padding: 1.25rem;
  max-height: calc(100vh - var(--header-height));
  overflow-y: auto;
}

.mobile-search-btn {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 1.25rem;
  cursor: pointer;
}

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

.mobile-nav-link {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.65rem 0.85rem;
  border-radius: var(--radius-md);
  color: var(--text-main);
  font-size: 0.95rem;
  font-weight: 500;
}

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

.mobile-nav-heading {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  font-weight: 700;
  padding: 0.75rem 0.85rem 0.25rem;
}

/* Main Site Content */
.site-main {
  flex: 1 0 auto;
}

/* Hero Section */
.hero-section {
  padding: 4rem 1.5rem 3rem;
  text-align: center;
  background: radial-gradient(circle at 50% 0%, var(--primary-light) 0%, transparent 70%);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.35rem 0.85rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 9999px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary);
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow-sm);
  max-width: 100%;
}

.hero-title {
  font-size: 2.75rem;
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.03em;
  color: var(--text-main);
  max-width: 820px;
  margin: 0 auto 1.25rem;
}

.hero-subtitle {
  font-size: 1.15rem;
  line-height: 1.6;
  color: var(--text-muted);
  max-width: 680px;
  margin: 0 auto 2.25rem;
}

/* Hero Search Box */
.hero-search-wrapper {
  max-width: 640px;
  margin: 0 auto 1.5rem;
  position: relative;
}

.hero-search-bar {
  display: flex;
  align-items: center;
  background-color: var(--bg-card);
  border: 2px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 0.5rem 0.75rem 0.5rem 1.25rem;
  box-shadow: var(--shadow-lg);
  transition: all var(--transition-fast);
}

.hero-search-bar:focus-within {
  border-color: var(--primary);
  box-shadow: 0 0 0 4px var(--primary-focus);
}

.hero-search-icon {
  color: var(--primary);
  margin-right: 0.75rem;
  display: flex;
  align-items: center;
}

.hero-search-input {
  flex: 1;
  min-width: 0;
  border: none;
  background: transparent;
  outline: none;
  font-size: 1.05rem;
  color: var(--text-main);
}

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

.hero-search-btn {
  background-color: var(--primary);
  color: #FFFFFF;
  border: none;
  padding: 0.65rem 1.35rem;
  border-radius: var(--radius-lg);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background var(--transition-fast);
}

.hero-search-btn:hover {
  background-color: var(--primary-hover);
}

/* Live Search Dropdown */
.hero-live-results {
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  right: 0;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  z-index: 50;
  max-height: 380px;
  overflow-y: auto;
  text-align: left;
}

.live-result-item {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  padding: 0.85rem 1.15rem;
  border-bottom: 1px solid var(--border);
  color: var(--text-main);
  transition: background var(--transition-fast);
}

.live-result-item:last-child {
  border-bottom: none;
}

.live-result-item:hover {
  background-color: var(--primary-light);
  color: var(--primary);
}

.live-result-info {
  flex: 1;
}

.live-result-title {
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 0.15rem;
}

.live-result-desc {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Hero Suggestion Chips */
.hero-suggestions {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2rem;
}

.suggestions-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

.suggestion-chip {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-main);
  padding: 0.35rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.825rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.suggestion-chip:hover {
  border-color: var(--primary);
  color: var(--primary);
  background-color: var(--primary-light);
}

.hero-cta-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  font-size: 1rem;
  color: var(--primary);
  padding: 0.5rem 1rem;
}

.hero-cta-btn:hover {
  text-decoration: underline;
}

/* Section Common Styles */
.section {
  padding: 4rem 1.5rem;
}

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

.section-header {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 3rem;
}

.section-kicker {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--primary);
  margin-bottom: 0.5rem;
}

.section-title {
  font-size: 2.1rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  color: var(--text-main);
  margin-bottom: 0.85rem;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-muted);
}

/* Calculator Grid & Cards */
.calculators-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
}

.calculator-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
  position: relative;
}

.calculator-card:hover {
  transform: translateY(-3px);
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

.card-top {
  margin-bottom: 1.25rem;
}

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

.card-icon-box {
  width: 2.75rem;
  height: 2.75rem;
  background-color: var(--primary-light);
  color: var(--primary);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
}

.card-icon-box .icon {
  width: 1.5rem;
  height: 1.5rem;
}

.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.6rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.badge-primary {
  background-color: var(--primary-light);
  color: var(--primary);
}

.badge-success {
  background-color: var(--success-light);
  color: var(--success);
}

.badge-neutral {
  background-color: var(--bg-card-subtle);
  color: var(--text-muted);
  border: 1px solid var(--border);
}

.card-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 0.5rem;
  line-height: 1.35;
}

.card-desc {
  font-size: 0.925rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.card-bottom {
  border-top: 1px solid var(--border);
  padding-top: 1rem;
  margin-top: 1.25rem;
}

.card-action-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-weight: 600;
  font-size: 0.925rem;
  color: var(--primary);
}

.card-action-link:hover {
  gap: 0.65rem;
}

/* Category Grid & Cards */
.categories-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
}

.category-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
}

.category-card:hover {
  transform: translateY(-3px);
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

.category-icon-box {
  width: 3rem;
  height: 3rem;
  border-radius: var(--radius-md);
  background-color: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.25rem;
}

.category-icon-box .icon {
  width: 1.6rem;
  height: 1.6rem;
}

.category-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 0.5rem;
}

.category-desc {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
  flex-grow: 1;
}

.category-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid var(--border);
  padding-top: 1rem;
  font-size: 0.85rem;
}

.category-count {
  color: var(--text-muted);
  font-weight: 500;
}

.category-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-weight: 600;
  color: var(--primary);
}

/* Why Use CalculatorTools & How it Works */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 2rem;
}

.feature-box {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  text-align: left;
}

.feature-icon {
  width: 2.75rem;
  height: 2.75rem;
  border-radius: var(--radius-md);
  background-color: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1rem;
}

.feature-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 0.5rem;
}

.feature-text {
  font-size: 0.925rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* How It Works Steps */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 2rem;
  position: relative;
}

.step-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  position: relative;
}

.step-number {
  position: absolute;
  top: 1.25rem;
  right: 1.5rem;
  font-size: 2.25rem;
  font-weight: 900;
  color: var(--border);
  line-height: 1;
}

.step-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 0.65rem;
}

.step-desc {
  font-size: 0.925rem;
  color: var(--text-muted);
}

/* FAQ Accordion */
.faq-container {
  max-width: 800px;
  margin: 0 auto;
}

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

.faq-item:hover {
  border-color: var(--primary);
}

.faq-trigger {
  width: 100%;
  padding: 1.15rem 1.35rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  background: none;
  border: none;
  text-align: left;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-main);
  cursor: pointer;
}

.faq-trigger .icon {
  color: var(--primary);
  transition: transform var(--transition-fast);
}

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

.faq-answer {
  display: none;
  padding: 0 1.35rem 1.25rem;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.6;
  border-top: 1px solid transparent;
}

.faq-item.open .faq-answer {
  display: block;
}

/* Calculator Page Layout */
.calculator-page-wrapper {
  padding: 2rem 1.5rem 4rem;
  max-width: var(--container-max);
  margin: 0 auto;
}

.calc-header-section {
  margin-bottom: 2rem;
}

.breadcrumb-nav {
  margin-bottom: 1.25rem;
}

.breadcrumb-list {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: var(--text-muted);
}

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

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

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

.breadcrumb-separator {
  color: var(--border);
  display: flex;
  align-items: center;
}

.breadcrumb-separator .icon {
  width: 0.85rem;
  height: 0.85rem;
}

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

/* Tool Logo & Header Display */
.calc-header-top {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: 1.25rem;
}

.tool-logo-box {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  filter: drop-shadow(0 4px 12px rgba(37, 99, 235, 0.22));
  transition: transform var(--transition-fast);
}

.tool-logo-box:hover {
  transform: scale(1.04);
}

.tool-logo-box svg {
  width: 100%;
  height: 100%;
  display: block;
}

.calc-header-meta {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  flex: 1;
  min-width: 0;
}

.calc-badge-row {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.calculator-card .tool-logo-box {
  width: 42px !important;
  height: 42px !important;
  border-radius: var(--radius-md);
  filter: drop-shadow(0 2px 6px rgba(37, 99, 235, 0.15));
}

.calc-title {
  font-size: 2.35rem;
  font-weight: 800;
  letter-spacing: -0.025em;
  color: var(--text-main);
  margin-bottom: 0.85rem;
  line-height: 1.25;
}

.calc-intro {
  font-size: 1.1rem;
  color: var(--text-muted);
  line-height: 1.6;
  max-width: 900px;
}

.calc-meta-bar {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 1.25rem;
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--text-muted);
}

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

/* Calculator Card Form Container */
.calculator-app-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 2rem;
  box-shadow: var(--shadow-md);
  margin-bottom: 3rem;
}

.form-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
  margin-bottom: 2rem;
}

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

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

.form-group label {
  font-weight: 600;
  font-size: 0.925rem;
  color: var(--text-main);
  margin-bottom: 0.4rem;
}

.form-group label .required {
  color: var(--danger);
}

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

.input-wrapper input,
.inline-grid-2 input,
.form-select {
  width: 100%;
  padding: 0.7rem 0.95rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 1rem;
  color: var(--text-main);
  outline: none;
  transition: all var(--transition-fast);
}

.input-wrapper input:focus,
.inline-grid-2 input:focus,
.form-select:focus {
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--primary-focus);
}

.unit-badge {
  position: absolute;
  right: 0.75rem;
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 500;
  pointer-events: none;
}

.currency-prefix {
  position: absolute;
  left: 0.85rem;
  color: var(--text-muted);
  font-weight: 600;
  pointer-events: none;
}

.input-wrapper input[placeholder="0.00"] {
  padding-left: 1.75rem;
}

.help-text {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.35rem;
}

.inline-grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.form-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.65rem 1.25rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all var(--transition-fast);
}

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

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

.btn-secondary {
  background-color: var(--bg-card-subtle);
  border-color: var(--border);
  color: var(--text-main);
}

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

.btn-outline {
  background-color: transparent;
  border-color: var(--border);
  color: var(--text-main);
}

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

.btn-large {
  padding: 0.85rem 1.75rem;
  font-size: 1.05rem;
  border-radius: var(--radius-lg);
}

.btn-sm {
  padding: 0.4rem 0.8rem;
  font-size: 0.85rem;
}

.form-error-msg {
  margin-top: 1rem;
  padding: 0.85rem 1.25rem;
  background-color: rgba(220, 38, 38, 0.1);
  border: 1px solid var(--danger);
  border-radius: var(--radius-md);
  color: var(--danger);
  font-size: 0.9rem;
}

/* Results Panel */
.results-panel {
  margin-top: 2.5rem;
  padding-top: 2.5rem;
  border-top: 2px dashed var(--border);
}

.results-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1.75rem;
}

.results-title-group h3 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-main);
  margin-top: 0.35rem;
}

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

/* Metric Cards */
.metrics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.25rem;
  margin-bottom: 2rem;
}

.metric-card {
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
}

.metric-primary {
  background-color: var(--primary-light);
  border-color: var(--primary);
}

.metric-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 0.5rem;
}

.metric-primary .metric-label {
  color: var(--primary);
}

.metric-value {
  font-size: 2rem;
  font-weight: 800;
  color: var(--text-main);
  line-height: 1.15;
  margin-bottom: 0.35rem;
}

.metric-primary .metric-value {
  color: var(--primary);
}

.metric-sub {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Breakdown Table */
.breakdown-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.breakdown-card h4 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--text-main);
}

.table-responsive {
  width: 100%;
  overflow-x: auto;
}

.breakdown-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
  text-align: left;
}

.breakdown-table th {
  background-color: var(--bg-card-subtle);
  padding: 0.75rem 1rem;
  font-weight: 600;
  color: var(--text-muted);
  border-bottom: 2px solid var(--border);
}

.breakdown-table td {
  padding: 0.85rem 1rem;
  border-bottom: 1px solid var(--border);
  color: var(--text-main);
}

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

.info-alert {
  display: flex;
  align-items: flex-start;
  gap: 0.85rem;
  padding: 1rem 1.25rem;
  background-color: var(--primary-light);
  border: 1px solid var(--primary);
  border-radius: var(--radius-md);
  color: var(--text-main);
  font-size: 0.925rem;
  line-height: 1.5;
}

.info-alert .icon {
  color: var(--primary);
  margin-top: 0.15rem;
}

/* Guide Content & Explanations */
.guide-article {
  max-width: 900px;
  margin: 0 auto 3rem;
  line-height: 1.7;
}

.guide-article h2 {
  font-size: 1.85rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-main);
  margin: 2.5rem 0 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
}

.guide-article h3 {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 1.75rem 0 0.75rem;
}

.guide-article h4 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-main);
  margin: 1.25rem 0 0.5rem;
}

.guide-article p {
  color: var(--text-main);
  margin-bottom: 1.25rem;
}

.guide-article ul, .guide-article ol {
  margin: 1rem 0 1.5rem 1.5rem;
}

.guide-article li {
  margin-bottom: 0.5rem;
  color: var(--text-main);
}

.guide-article ul {
  list-style: disc;
}

.guide-article ol {
  list-style: decimal;
}

.formula-box {
  background-color: var(--bg-card-subtle);
  border-left: 4px solid var(--primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: 1rem 1.25rem;
  margin: 1rem 0 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  overflow-x: auto;
}

.formula-box code {
  display: block;
  margin-bottom: 0.35rem;
  color: var(--text-main);
}

.formula-box code:last-child {
  margin-bottom: 0;
}

/* Editorial / Reviewer Badge */
.editorial-box {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin-top: 3rem;
}

.editorial-avatar {
  width: 3.5rem;
  height: 3.5rem;
  border-radius: 9999px;
  background-color: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.editorial-title {
  font-weight: 700;
  font-size: 1rem;
  color: var(--text-main);
  margin-bottom: 0.25rem;
}

.editorial-text {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* Related Calculators Grid */
.related-section {
  margin-top: 4rem;
  padding-top: 3rem;
  border-top: 1px solid var(--border);
}

.related-section h3 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
  color: var(--text-main);
}

/* AdSense Slot Styles */
.adsense-wrapper {
  margin: 2.5rem auto;
  text-align: center;
}

.adsense-label {
  font-size: 0.725rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 0.4rem;
  font-weight: 600;
}

.adsense-box {
  background-color: var(--bg-card-subtle);
  border: 1px dashed var(--border);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  min-height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color var(--transition-fast);
}

.adsense-placeholder-inner {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.ads-text {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-muted);
}

.ads-sub {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.adsense-hero {
  max-width: 728px;
  margin: 1.5rem auto 2.5rem;
}

.adsense-hero .adsense-box {
  min-height: 90px;
  contain: layout;
}

.adsense-mid {
  max-width: 970px;
}

.adsense-mid .adsense-box {
  min-height: 250px;
  contain: layout;
}

.adsense-article {
  max-width: 100%;
}

.adsense-article .adsense-box {
  min-height: 250px;
  contain: layout;
}

.adsense-footer {
  max-width: 728px;
  margin-bottom: 3rem;
}

.adsense-footer .adsense-box {
  min-height: 90px;
  contain: layout;
}

.adsense-multiplex {
  max-width: var(--container-max);
  margin: 2.5rem auto 3rem;
}

.adsense-multiplex .adsense-box {
  min-height: 220px;
  contain: layout;
}

.multiplex-placeholder-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  width: 100%;
  padding: 0.75rem;
}

.multiplex-placeholder-card {
  background: var(--bg-card);
  border: 1px dashed var(--border);
  border-radius: var(--radius-md);
  padding: 1.25rem 0.75rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  gap: 0.25rem;
}

@media (max-width: 768px) {
  .multiplex-placeholder-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 480px) {
  .multiplex-placeholder-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  .adsense-hero .adsense-box {
    min-height: 100px;
  }
  .adsense-mid .adsense-box,
  .adsense-article .adsense-box {
    min-height: 250px;
  }
  .adsense-footer .adsense-box {
    min-height: 100px;
  }
  .adsense-multiplex .adsense-box {
    min-height: 280px;
  }
}

/* Search Modal Overlay */
.search-modal-backdrop {
  position: fixed;
  inset: 0;
  background-color: rgba(15, 23, 42, 0.65);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  z-index: 200;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 4rem 1rem 2rem;
  animation: fadeIn 150ms ease;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.search-modal-container {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl);
  width: 100%;
  max-width: 640px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.search-modal-header {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 1rem;
}

.search-input-group {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.search-input-group input {
  flex: 1;
  border: none;
  background: transparent;
  outline: none;
  font-size: 1.1rem;
  color: var(--text-main);
}

.kbd-shortcut {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  background: var(--bg-card-subtle);
  border: 1px solid var(--border);
  padding: 0.15rem 0.4rem;
  border-radius: var(--radius-sm);
  color: var(--text-muted);
}

.btn-icon {
  background: transparent;
  border: none;
  cursor: pointer;
  color: var(--text-muted);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  padding: 0.5rem;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.btn-icon:hover {
  color: var(--text-main);
  background-color: var(--bg-card-subtle);
}

.search-modal-body {
  padding: 1rem 1.25rem;
  max-height: 420px;
  overflow-y: auto;
}

.search-quick-tags {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}

.quick-tag-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
}

.search-chip {
  background: var(--bg-card-subtle);
  border: 1px solid var(--border);
  border-radius: 9999px;
  padding: 0.25rem 0.65rem;
  font-size: 0.8rem;
  cursor: pointer;
  color: var(--text-main);
  transition: all var(--transition-fast);
}

.search-chip:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.search-result-item {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 0.85rem;
  border-radius: var(--radius-md);
  color: var(--text-main);
  transition: background var(--transition-fast);
}

.search-result-item:hover {
  background-color: var(--primary-light);
  color: var(--primary);
}

.search-empty-state {
  text-align: center;
  padding: 2.5rem 1rem;
  color: var(--text-muted);
}

/* Toast Notification */
.toast {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background-color: var(--secondary);
  color: #FFFFFF;
  padding: 0.85rem 1.5rem;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-xl);
  font-weight: 500;
  font-size: 0.95rem;
  z-index: 300;
  animation: slideUp 200ms ease;
}

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

/* Footer */
.site-footer {
  background-color: var(--bg-card);
  border-top: 1px solid var(--border);
  padding: 4.5rem 1.5rem 2.5rem;
  margin-top: auto;
}

.footer-container {
  max-width: var(--container-max);
  margin: 0 auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 3rem;
  margin-bottom: 3.5rem;
}

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

@media (max-width: 540px) {
  .footer-grid {
    grid-template-columns: 1fr;
  }
}

.footer-brand-col {
  padding-right: 1.5rem;
}

.footer-tagline {
  font-weight: 600;
  color: var(--primary);
  font-size: 0.95rem;
  margin: 0.65rem 0 0.5rem;
}

.footer-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 1.25rem;
}

.footer-badge-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
}

.footer-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.8rem;
  font-weight: 600;
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border);
  padding: 0.3rem 0.65rem;
  border-radius: 9999px;
  color: var(--text-main);
}

.footer-heading {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-main);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 1.25rem;
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.footer-links a {
  color: var(--text-muted);
  font-size: 0.9rem;
  transition: color var(--transition-fast);
}

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

.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  font-size: 0.875rem;
  color: var(--text-muted);
}

.footer-bottom-links {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  row-gap: 0.4rem;
  column-gap: 0.75rem;
}

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

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

/* Category Filter Tabs for All Calculators Page */
.category-filter-bar {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  overflow-x: auto;
  padding-bottom: 0.5rem;
  margin-bottom: 2rem;
}

.filter-tab {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 0.5rem 1rem;
  border-radius: 9999px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition-fast);
}

.filter-tab.active, .filter-tab:hover {
  background-color: var(--primary);
  border-color: var(--primary);
  color: #FFFFFF;
}

/* Print Stylesheet */
@media print {
  .site-header,
  .site-footer,
  .search-modal-backdrop,
  .adsense-wrapper,
  .form-actions,
  .results-actions,
  .related-section,
  .faq-container,
  .hero-suggestions,
  .hero-search-wrapper,
  .breadcrumb-nav,
  .editorial-box,
  #toast {
    display: none !important;
  }

  body, html {
    background: #FFFFFF !important;
    color: #000000 !important;
    font-size: 12pt;
  }

  .calculator-app-card, .results-panel {
    border: none !important;
    box-shadow: none !important;
    padding: 0 !important;
    margin: 0 !important;
  }

  .results-panel {
    display: block !important;
  }

  .metric-card {
    border: 1px solid #CCCCCC !important;
    background: #FAFAFA !important;
  }

  .breakdown-table th, .breakdown-table td {
    border: 1px solid #DDDDDD !important;
    color: #000000 !important;
  }
}

/* Guide System & Hub Base Styles */
.guides-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.75rem;
}

.guide-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
}

.guide-card:hover {
  transform: translateY(-3px);
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

.guide-badge-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.guide-read-time {
  font-size: 0.8rem;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.guide-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.35;
  margin-bottom: 0.75rem;
}

.guide-desc {
  font-size: 0.925rem;
  color: var(--text-muted);
  line-height: 1.55;
  margin-bottom: 1.25rem;
}

.guide-calc-cta {
  background: linear-gradient(135deg, var(--primary-light), var(--bg-card-subtle));
  border: 1px solid var(--primary);
  border-radius: var(--radius-lg);
  padding: 1.5rem 1.75rem;
  margin: 2rem 0 2.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1.25rem;
}

.guide-calc-cta-info h3 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 0.35rem;
}

.guide-calc-cta-info p {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin: 0;
}

/* ==========================================================================
   Comprehensive Mobile-First Responsive System
   ========================================================================== */

/* 1. Medium Tablets & Small Desktops (<= 900px) */
@media (max-width: 900px) {
  .desktop-nav {
    display: none;
  }
  .mobile-menu-btn {
    display: flex;
  }
  .header-container {
    gap: 1rem;
  }
  .hero-title {
    font-size: 2.25rem;
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 2.5rem;
  }
}

/* 2. Small Tablets & Landscape Mobile (<= 768px) */
@media (max-width: 768px) {
  .header-container {
    padding: 0 1rem;
    gap: 0.5rem;
    height: 62px;
  }
  .brand-logo {
    font-size: 1.2rem;
    gap: 0.5rem;
  }
  .logo-icon-box {
    width: 2rem;
    height: 2rem;
  }
  .logo-icon-box .icon {
    width: 1.15rem;
    height: 1.15rem;
  }
  .header-actions {
    gap: 0.4rem;
  }
  .search-trigger-btn .search-btn-text,
  .search-trigger-btn .kbd-pill {
    display: none;
  }
  .search-trigger-btn {
    width: 40px;
    height: 40px;
    min-width: 40px;
    min-height: 40px;
    padding: 0;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-md);
  }
  .theme-toggle-btn,
  .mobile-menu-btn {
    width: 40px;
    height: 40px;
    min-width: 40px;
    min-height: 40px;
    padding: 0;
  }

  .container {
    padding-left: 1rem;
    padding-right: 1rem;
  }

  .hero-section {
    padding: 3rem 1rem 2rem;
  }
  .hero-title {
    font-size: 1.95rem;
    line-height: 1.25;
  }
  .hero-subtitle {
    font-size: 1rem;
    line-height: 1.5;
    margin-bottom: 1.75rem;
  }
  .hero-badge {
    font-size: 0.775rem;
    padding: 0.3rem 0.75rem;
    white-space: normal;
    text-align: center;
    max-width: 100%;
  }

  .form-grid {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }
  .calculator-page-wrapper {
    padding: 1.5rem 1rem 3rem;
  }
}

/* 3. Smartphones & Portrait Mobile (<= 640px) */
@media (max-width: 640px) {
  /* Navigation Bar */
  .site-header {
    border-bottom-color: var(--border);
  }
  .header-container {
    padding: 0 0.75rem;
    gap: 0.35rem;
    height: 58px;
  }
  .brand-logo {
    font-size: 1.1rem;
    gap: 0.4rem;
    flex-shrink: 1;
    min-width: 0;
  }
  .brand-logo .logo-text {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
  }
  .logo-icon-box {
    width: 1.85rem;
    height: 1.85rem;
    border-radius: var(--radius-sm);
    flex-shrink: 0;
  }
  .header-actions {
    gap: 0.3rem;
    flex-shrink: 0;
  }
  .search-trigger-btn,
  .theme-toggle-btn,
  .mobile-menu-btn {
    width: 38px;
    height: 38px;
    min-width: 38px;
    min-height: 38px;
    border-radius: var(--radius-md);
  }

  /* Hero Section */
  .hero-section {
    padding: 2.25rem 0.75rem 1.75rem;
  }
  .hero-badge {
    font-size: 0.75rem;
    padding: 0.25rem 0.65rem;
    border-radius: var(--radius-md);
    margin-bottom: 1rem;
    display: inline-flex;
    line-height: 1.35;
  }
  .hero-title {
    font-size: 1.65rem;
    line-height: 1.22;
    margin-bottom: 0.75rem;
    word-break: break-word;
  }
  .hero-subtitle {
    font-size: 0.925rem;
    line-height: 1.45;
    margin-bottom: 1.5rem;
  }

  /* Search Input & Controls */
  .hero-search-wrapper {
    margin-bottom: 1.25rem;
    width: 100%;
  }
  .hero-search-bar {
    padding: 0.3rem 0.35rem 0.3rem 0.75rem;
    border-radius: var(--radius-lg);
    border-width: 1.5px;
  }
  .hero-search-icon {
    margin-right: 0.4rem;
  }
  .hero-search-icon .icon {
    width: 1rem;
    height: 1rem;
  }
  .hero-search-input {
    font-size: 0.9rem;
  }
  .hero-search-btn {
    padding: 0.55rem 0.85rem;
    font-size: 0.85rem;
    border-radius: var(--radius-md);
    flex-shrink: 0;
    white-space: nowrap;
  }

  /* Suggestion Chips */
  .hero-suggestions {
    gap: 0.35rem;
    margin-bottom: 1.5rem;
  }
  .suggestions-label {
    font-size: 0.775rem;
  }
  .suggestion-chip {
    padding: 0.25rem 0.6rem;
    font-size: 0.775rem;
  }

  /* Grids: Responsive 1-Column Stack */
  .calculators-grid,
  .categories-grid,
  .guides-grid,
  .features-grid,
  .steps-grid {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }

  .calculator-card,
  .category-card,
  .guide-card,
  .feature-box,
  .step-card {
    padding: 1.25rem;
    border-radius: var(--radius-md);
  }

  /* Sections */
  .section {
    padding: 2.5rem 0;
  }
  .section-title {
    font-size: 1.5rem;
  }
  .section-desc {
    font-size: 0.925rem;
  }

  /* Calculator Application Experience */
  .calculator-page-wrapper {
    padding: 1rem 0.85rem 2.5rem;
  }
  .breadcrumb-nav {
    margin-bottom: 0.85rem;
  }
  .breadcrumb-list {
    font-size: 0.775rem;
    gap: 0.35rem;
    line-height: 1.4;
  }
  .calc-header-section {
    margin-bottom: 1.5rem;
  }
  .calc-header-top {
    gap: 0.85rem;
    align-items: flex-start;
    margin-bottom: 1rem;
  }
  .tool-logo-box {
    width: 50px !important;
    height: 50px !important;
    border-radius: var(--radius-md);
  }
  .calc-title {
    font-size: 1.55rem;
    line-height: 1.25;
    word-break: break-word;
  }
  .calc-intro {
    font-size: 0.925rem;
    line-height: 1.5;
  }
  .calc-meta-bar {
    gap: 0.75rem;
    font-size: 0.8rem;
  }
  .calculator-app-card {
    padding: 1.25rem 0.85rem;
    border-radius: var(--radius-lg);
    margin-bottom: 2rem;
  }
  .form-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
    margin-bottom: 1.5rem;
  }
  .inline-grid-2 {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }
  .form-actions {
    flex-direction: column;
    width: 100%;
    gap: 0.75rem;
  }
  .form-actions .btn {
    width: 100%;
    justify-content: center;
    padding: 0.75rem;
  }
  .results-panel {
    margin-top: 1.75rem;
    padding-top: 1.75rem;
  }
  .results-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }
  .results-title-group h3 {
    font-size: 1.3rem;
  }
  .results-actions {
    width: 100%;
    flex-direction: column;
    gap: 0.5rem;
  }
  .results-actions .btn {
    width: 100%;
    justify-content: center;
  }
  .metrics-grid {
    grid-template-columns: 1fr;
    gap: 0.85rem;
    margin-bottom: 1.5rem;
  }
  .metric-card {
    padding: 1rem;
  }
  .metric-value {
    font-size: 1.65rem;
  }
  .breakdown-card {
    padding: 0.85rem;
  }
  .breakdown-table th,
  .breakdown-table td {
    padding: 0.6rem 0.75rem;
    font-size: 0.825rem;
  }
  .guide-article {
    padding: 1.15rem 0.85rem;
  }
  .guide-article h2 {
    font-size: 1.3rem;
  }
  .guide-article h3 {
    font-size: 1.1rem;
  }
  .guide-calc-cta {
    padding: 1.25rem 1rem;
    flex-direction: column;
    align-items: flex-start;
  }
  .guide-calc-cta .btn {
    width: 100%;
    justify-content: center;
  }

  /* Search Modal Mobile */
  .search-modal-backdrop {
    padding: 1rem 0.5rem;
  }
  .search-modal-container {
    border-radius: var(--radius-lg);
    max-height: 90vh;
  }
  .kbd-shortcut {
    display: none;
  }
  .search-modal-header {
    padding: 0.75rem 1rem;
  }
  .search-input-group input {
    font-size: 0.95rem;
  }
  .search-modal-body {
    padding: 0.85rem 1rem;
  }

  /* Footer Mobile */
  .site-footer {
    padding: 3rem 1rem 2.5rem;
  }
  .footer-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-bottom: 2rem;
  }
  .footer-brand-col {
    padding-right: 0;
  }
  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.85rem;
    padding-top: 1.5rem;
  }
  .footer-copyright {
    font-size: 0.825rem;
    line-height: 1.5;
  }
  .footer-bottom-links {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    row-gap: 0.4rem;
    column-gap: 0.65rem;
    font-size: 0.825rem;
  }
}

/* 4. Ultra-Narrow Smartphones (<= 380px, e.g. iPhone 5/SE, Galaxy Fold cover) */
@media (max-width: 380px) {
  .header-container {
    padding: 0 0.5rem;
    gap: 0.25rem;
  }
  .brand-logo .logo-text {
    font-size: 1rem;
  }
  .search-trigger-btn,
  .theme-toggle-btn,
  .mobile-menu-btn {
    width: 35px;
    height: 35px;
    min-width: 35px;
    min-height: 35px;
  }
  .hero-title {
    font-size: 1.45rem;
  }
  .hero-search-bar {
    padding: 0.25rem 0.3rem 0.25rem 0.6rem;
  }
  .hero-search-btn {
    padding: 0.45rem 0.75rem;
    font-size: 0.8rem;
  }
  .metric-value {
    font-size: 1.45rem;
  }
  .calculator-page-wrapper {
    padding: 0.75rem 0.5rem 2rem;
  }
  .calc-header-top {
    gap: 0.65rem;
  }
  .tool-logo-box {
    width: 40px !important;
    height: 40px !important;
  }
  .calculator-app-card {
    padding: 1rem 0.65rem;
  }
  .footer-bottom-links {
    font-size: 0.775rem;
    column-gap: 0.45rem;
  }
}