/* ==========================================================================
   FreeAITool.net — Complete Responsive Design System
   ========================================================================== */

:root {
  --color-primary: #1e40af;
  --color-primary-hover: #1d4ed8;
  --color-primary-light: #eff6ff;
  --color-accent: #059669;
  --color-accent-hover: #047857;
  --color-accent-light: #ecfdf5;
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-border: #e2e8f0;
  --color-border-input: #cbd5e1;
  --color-border-subtle: #f1f5f9;
  --color-text-main: #0f172a;
  --color-text-muted: #334155;
  --color-text-light: #64748b;
  --color-danger: #dc2626;
  --color-danger-light: #fef2f2;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.07), 0 2px 4px -2px rgb(0 0 0 / 0.07);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.08), 0 4px 6px -4px rgb(0 0 0 / 0.08);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

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

html {
  font-family: var(--font-family);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text-main);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--color-bg);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.15s ease;
}

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

/* Layout Container */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

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

.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 40;
  box-shadow: var(--shadow-sm);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.25rem;
  gap: 1.5rem;
}

.brand-link {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 800;
  font-size: 1.3rem;
  color: var(--color-text-main);
  text-decoration: none !important;
}

.brand-logo-icon {
  width: 2.25rem;
  height: 2.25rem;
  background: linear-gradient(135deg, var(--color-primary) 0%, #3b82f6 100%);
  color: white;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  box-shadow: 0 2px 4px rgba(30, 64, 175, 0.2);
}

.brand-badge {
  font-size: 0.7rem;
  background: var(--color-accent-light);
  color: var(--color-accent);
  padding: 0.2rem 0.6rem;
  border-radius: 9999px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  border: 1px solid #a7f3d0;
}

.nav-desktop {
  display: none;
  align-items: center;
  gap: 1.5rem;
}

@media (min-width: 860px) {
  .nav-desktop {
    display: flex;
  }
}

.nav-link {
  color: var(--color-text-muted);
  font-weight: 600;
  font-size: 0.95rem;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
  text-decoration: none !important;
  transition: all 0.15s ease;
}

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

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

.search-trigger-btn {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  background: var(--color-bg);
  border: 1.5px solid var(--color-border);
  color: var(--color-text-light);
  padding: 0.55rem 0.95rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s ease;
}

.search-trigger-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-text-main);
  background: var(--color-surface);
  box-shadow: var(--shadow-sm);
}

.search-shortcut-badge {
  background: var(--color-border);
  padding: 0.1rem 0.4rem;
  border-radius: 4px;
  font-size: 0.75rem;
  font-family: monospace;
  font-weight: 600;
  color: var(--color-text-muted);
}

.mobile-nav-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-bg);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 0.5rem;
  cursor: pointer;
  color: var(--color-text-main);
}

@media (min-width: 860px) {
  .mobile-nav-toggle {
    display: none;
  }
}

.mobile-menu {
  display: none;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: 1rem 1.25rem;
  box-shadow: var(--shadow-md);
}

.mobile-menu.open {
  display: block;
}

.mobile-menu-links {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.mobile-menu-link {
  padding: 0.75rem 1rem;
  font-weight: 600;
  font-size: 1rem;
  border-radius: var(--radius-sm);
  color: var(--color-text-main);
  text-decoration: none !important;
}

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

/* ==========================================================================
   Search Modal
   ========================================================================== */

.search-modal-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.6);
  backdrop-filter: blur(4px);
  z-index: 50;
  align-items: flex-start;
  justify-content: center;
  padding: 4rem 1rem 1rem;
}

.search-modal-backdrop.open {
  display: flex;
}

.search-modal-card {
  background: var(--color-surface);
  width: 100%;
  max-width: 600px;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  max-height: 80vh;
}

.search-modal-header {
  display: flex;
  align-items: center;
  padding: 0.85rem 1.25rem;
  border-bottom: 1px solid var(--color-border);
  gap: 0.75rem;
  background: var(--color-surface);
}

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

.search-modal-close {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  cursor: pointer;
  color: var(--color-text-light);
  width: 2rem;
  height: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.search-results-list {
  overflow-y: auto;
  padding: 0.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.search-result-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.85rem 1rem;
  border-radius: var(--radius-md);
  text-decoration: none !important;
  color: var(--color-text-main);
  transition: background 0.15s ease;
}

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

.search-result-title {
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--color-text-main);
}

.search-result-desc {
  font-size: 0.825rem;
  color: var(--color-text-light);
  margin-top: 0.15rem;
}

.search-result-badge {
  font-size: 0.7rem;
  font-weight: 600;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  padding: 0.25rem 0.6rem;
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
}

/* ==========================================================================
   Breadcrumbs & Page Header
   ========================================================================== */

.page-main {
  flex: 1;
  padding: 2rem 0 4rem;
}

.breadcrumbs {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: var(--color-text-light);
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.breadcrumbs a {
  color: var(--color-text-light);
  text-decoration: none;
}

.breadcrumbs a:hover {
  color: var(--color-primary);
  text-decoration: underline;
}

.breadcrumb-separator {
  color: #94a3b8;
}

.page-title {
  font-size: 2.25rem;
  font-weight: 800;
  line-height: 1.25;
  color: var(--color-text-main);
  margin-bottom: 0.75rem;
  letter-spacing: -0.02em;
}

.page-lead {
  font-size: 1.125rem;
  color: var(--color-text-muted);
  max-width: 840px;
  margin-bottom: 2.25rem;
  line-height: 1.6;
}

/* ==========================================================================
   Tool Grid & Layout Cards
   ========================================================================== */

.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.category-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  transition: all 0.2s ease;
  display: flex;
  flex-direction: column;
}

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

.category-card-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.category-card-icon {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius-md);
  background: var(--color-primary-light);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
}

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

.category-card-desc {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin-bottom: 1.25rem;
  flex: 1;
  line-height: 1.5;
}

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

.category-tool-link {
  font-size: 0.9rem;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.category-view-all {
  margin-top: 1.25rem;
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--color-primary);
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

/* ==========================================================================
   Calculator 2-Column Responsive Layout
   ========================================================================== */

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

@media (min-width: 960px) {
  .calculator-layout {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
    align-items: start;
  }
}

.calc-panel {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
}

.calc-panel-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
  color: var(--color-text-main);
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--color-border-subtle);
}

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

.form-label {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 0.45rem;
  color: var(--color-text-main);
}

.form-input, .form-select, .form-textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 1.5px solid var(--color-border-input);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-family: inherit;
  color: var(--color-text-main);
  background: var(--color-surface);
  transition: all 0.15s ease;
}

.form-input:focus, .form-select:focus, .form-textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3.5px rgba(37, 99, 235, 0.18);
}

.form-hint {
  font-size: 0.8rem;
  color: var(--color-text-light);
  margin-top: 0.35rem;
}

.btn-group {
  display: flex;
  gap: 0.75rem;
  margin-top: 1.75rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.6rem;
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 0.95rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.15s ease;
  text-decoration: none !important;
  font-family: inherit;
}

.btn-primary {
  background: var(--color-primary);
  color: white;
  box-shadow: 0 2px 4px rgba(30, 64, 175, 0.2);
}

.btn-primary:hover {
  background: var(--color-primary-hover);
  box-shadow: 0 4px 6px rgba(30, 64, 175, 0.3);
}

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

.btn-secondary:hover {
  background: #e2e8f0;
}

/* Results Display */
.result-card {
  background: linear-gradient(135deg, #ecfdf5 0%, #f0fdf4 100%);
  border: 1.5px solid #6ee7b7;
  border-radius: var(--radius-md);
  padding: 1.75rem;
  margin-bottom: 1.5rem;
  text-align: center;
  box-shadow: var(--shadow-sm);
}

.result-label {
  font-size: 0.8rem;
  font-weight: 800;
  text-transform: uppercase;
  color: #047857;
  letter-spacing: 0.06em;
  margin-bottom: 0.35rem;
}

.result-value {
  font-size: 2.6rem;
  font-weight: 800;
  color: #064e3b;
  line-height: 1.15;
}

.result-subtext {
  font-size: 0.95rem;
  color: #047857;
  font-weight: 600;
  margin-top: 0.5rem;
}

/* Tables */
.table-responsive {
  width: 100%;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.result-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.925rem;
  margin-top: 1rem;
}

.result-table th, .result-table td {
  padding: 0.75rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.result-table th {
  background: var(--color-bg);
  font-weight: 700;
  color: var(--color-text-muted);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.result-table tbody tr:nth-child(even) {
  background: #fafafa;
}

/* ==========================================================================
   Editorial Content, Formulas & FAQ
   ========================================================================== */

.content-section {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 2.25rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-sm);
}

.section-title {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--color-text-main);
  margin-bottom: 1.25rem;
  letter-spacing: -0.01em;
}

.formula-box {
  background: var(--color-primary-light);
  border-left: 4.5px solid var(--color-primary);
  padding: 1.35rem;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 1.1rem;
  color: #1e3a8a;
  margin: 1.25rem 0;
  overflow-x: auto;
  font-weight: 600;
}

.faq-item {
  border-bottom: 1px solid var(--color-border);
  padding: 1.25rem 0;
}

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

.faq-question {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text-main);
  margin-bottom: 0.5rem;
}

.faq-answer {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  line-height: 1.7;
}

/* Trust Disclaimer Box */
.disclaimer-box {
  background: #fffbeb;
  border: 1px solid #fde68a;
  border-radius: var(--radius-md);
  padding: 1.25rem 1.5rem;
  font-size: 0.875rem;
  color: #92400e;
  margin-top: 2rem;
  line-height: 1.6;
}

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

.site-footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: 3.5rem 0 2rem;
  margin-top: auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2.25rem;
  margin-bottom: 2.5rem;
}

.footer-col-title {
  font-size: 0.95rem;
  font-weight: 800;
  text-transform: uppercase;
  color: var(--color-text-main);
  margin-bottom: 1.15rem;
  letter-spacing: 0.05em;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.footer-link {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  font-weight: 500;
}

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

.footer-bottom {
  border-top: 1px solid var(--color-border);
  padding-top: 1.75rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  font-size: 0.85rem;
  color: var(--color-text-light);
}

@media (min-width: 640px) {
  .footer-bottom {
    flex-direction: row;
  }
}