/* Color Palette & Custom Variable Tokens */
:root {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f5f9;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --brand-primary: #4f46e5;
  --brand-hover: #4338ca;
  --brand-light: #e0e7ff;
  --accent-color: #06b6d4;
  --border-color: #e2e8f0;
  --card-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.05), 0 2px 4px -2px rgb(0 0 0 / 0.05);
  --transition-speed: 0.2s;
  --max-width: 1200px;
}

[data-theme="dark"] {
  --bg-primary: #0b0f19;
  --bg-secondary: #111827;
  --bg-tertiary: #1f2937;
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --brand-primary: #6366f1;
  --brand-hover: #4f46e5;
  --brand-light: #1e1b4b;
  --border-color: #374151;
  --card-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.3), 0 2px 4px -2px rgb(0 0 0 / 0.3);
}

/* Global Reset & Typography */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color var(--transition-speed), color var(--transition-speed);
}
a {
  color: var(--brand-primary);
  text-decoration: none;
  transition: color var(--transition-speed);
}
a:hover {
  color: var(--brand-hover);
}

/* Navigation Layout */
header {
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(8px);
}
.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1rem 1.5rem;
}
.logo {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--brand-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.nav-links {
  display: flex;
  gap: 1.5rem;
  align-items: center;
  list-style-type: none;
}
.theme-toggle-btn {
  background: none;
  border: 1px solid var(--border-color);
  padding: 0.5rem;
  border-radius: 50%;
  cursor: pointer;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color var(--transition-speed);
}
.theme-toggle-btn:hover {
  border-color: var(--brand-primary);
}

/* Responsive Menu Styles */
.menu-btn {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: 1.5rem;
  cursor: pointer;
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--bg-secondary);
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    gap: 1rem;
  }
  .nav-links.active {
    display: flex;
  }
  .menu-btn {
    display: block;
  }
}

/* Main Container Hierarchy */
main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 4rem 1rem;
  background: radial-gradient(circle at top right, var(--brand-light), transparent 60%);
  border-radius: 1rem;
  margin-bottom: 3rem;
}
.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 1rem;
  line-height: 1.15;
}
.hero p {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto 2rem;
}
.search-wrapper {
  max-width: 550px;
  margin: 0 auto;
  position: relative;
}
.search-input {
  width: 100%;
  padding: 1.1rem 1.5rem;
  border-radius: 9999px;
  border: 1px solid var(--border-color);
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  font-size: 1.05rem;
  box-shadow: var(--card-shadow);
  outline: none;
  transition: border-color var(--transition-speed);
}
.search-input:focus {
  border-color: var(--brand-primary);
}

/* Grid & Layout Utilities */
.grid-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3rem;
}
.card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  padding: 1.5rem;
  transition: transform var(--transition-speed), box-shadow var(--transition-speed);
  box-shadow: var(--card-shadow);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}
.card:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.1);
}

/* Tabular Cost Comparisons */
.table-container {
  overflow-x: auto;
  margin: 2rem 0;
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  box-shadow: var(--card-shadow);
}
table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}
th, td {
  padding: 1rem;
  border-bottom: 1px solid var(--border-color);
}
th {
  background-color: var(--bg-tertiary);
  font-weight: 600;
  color: var(--text-primary);
}
tr:last-child td {
  border-bottom: none;
}

/* Interactive Calculator Module */
.calculator-box {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 1rem;
  padding: 2.5rem;
  margin: 2rem 0;
  box-shadow: var(--card-shadow);
}
.input-group {
  margin-bottom: 1.5rem;
}
.input-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}
.slider {
  width: 100%;
  height: 6px;
  background-color: var(--border-color);
  border-radius: 3px;
  outline: none;
  appearance: none;
}
.slider::-webkit-slider-thumb {
  appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background-color: var(--brand-primary);
  cursor: pointer;
}
.form-select, .form-control {
  width: 100%;
  padding: 0.8rem 1rem;
  border-radius: 0.5rem;
  border: 1px solid var(--border-color);
  background-color: var(--bg-primary);
  color: var(--text-primary);
}

/* Interactive Calculator Outputs */
.output-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  text-align: center;
  margin: 2rem 0;
}
.output-card {
  padding: 1rem;
  border-radius: 0.5rem;
  background-color: var(--bg-tertiary);
}
.output-card.highlight {
  background-color: var(--brand-light);
  color: var(--text-primary);
}
.output-val {
  font-size: 1.8rem;
  font-weight: 800;
  margin-top: 0.25rem;
  color: var(--brand-primary);
}

/* Accordion FAQs */
.faq-item {
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0;
}
.faq-question {
  width: 100%;
  background: none;
  border: none;
  text-align: left;
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.faq-answer {
  display: none;
  padding-top: 0.5rem;
  color: var(--text-secondary);
}
.faq-answer.active {
  display: block;
}

/* Editorial & Trust Badges */
.trust-badge-row {
  display: flex;
  gap: 2rem;
  justify-content: center;
  flex-wrap: wrap;
  margin: 3rem 0;
  text-align: center;
}
.trust-badge-row div {
  flex: 1;
  min-width: 200px;
  padding: 1.5rem;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
}

/* Footer Styles */
footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 4rem 1.5rem 2rem;
  color: var(--text-secondary);
}
.footer-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}
.footer-col h4 {
  color: var(--text-primary);
  margin-bottom: 1rem;
}
.footer-links {
  list-style-type: none;
}
.footer-links li {
  margin-bottom: 0.5rem;
}
.footer-bottom {
  max-width: var(--max-width);
  margin: 0 auto;
  border-top: 1px solid var(--border-color);
  padding-top: 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}