:root {
  --primary: #15803d;
  --primary-hover: #166534;
  --primary-light: #dcfce7;
  --secondary: #0369a1;
  --dark: #0f172a;
  --gray-dark: #334155;
  --gray-medium: #64748b;
  --gray-light: #f1f5f9;
  --border: #cbd5e1;
  --warning: #b45309;
  --warning-bg: #fef3c7;
  --white: #ffffff;
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--dark);
  background-color: #f8fafc;
  line-height: 1.6;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header & Nav */
header {
  background: var(--white);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 50;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 4.5rem;
}

.logo {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo span {
  color: var(--dark);
}

nav a {
  color: var(--gray-dark);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  margin-left: 1.5rem;
  transition: color 0.15s ease;
}

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

/* Hero Section */
.hero {
  background: linear-gradient(180deg, #f0fdf4 0%, #f8fafc 100%);
  padding: 3.5rem 0 2.5rem;
  text-align: center;
  border-bottom: 1px solid #e2e8f0;
}

.hero h1 {
  font-size: 2.75rem;
  font-weight: 800;
  color: var(--dark);
  line-height: 1.2;
  margin-bottom: 1rem;
}

.hero p {
  font-size: 1.2rem;
  color: var(--gray-dark);
  max-width: 800px;
  margin: 0 auto 1.5rem;
}

.alert-banner {
  background: var(--warning-bg);
  border: 1px solid #fde68a;
  border-radius: 8px;
  padding: 0.85rem 1.25rem;
  max-width: 850px;
  margin: 0 auto;
  font-size: 0.95rem;
  color: var(--warning);
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

/* Filter Controls */
.filter-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  margin: 2rem 0;
  box-shadow: var(--shadow);
}

.filter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  align-items: flex-end;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.form-group label {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--gray-dark);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.form-group select,
.form-group input {
  padding: 0.65rem 0.85rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 0.95rem;
  background-color: var(--white);
  color: var(--dark);
  outline: none;
  transition: border-color 0.15s;
}

.form-group select:focus,
.form-group input:focus {
  border-color: var(--primary);
}

/* Comparison Table & Cards */
.table-responsive {
  overflow-x: auto;
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow);
  margin-bottom: 3rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

th {
  background-color: #f8fafc;
  padding: 1rem 1.25rem;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--gray-dark);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  border-bottom: 2px solid var(--border);
}

td {
  padding: 1.15rem 1.25rem;
  border-bottom: 1px solid #f1f5f9;
  vertical-align: middle;
  font-size: 0.95rem;
}

tr:hover td {
  background-color: #f8fafc;
}

.badge {
  display: inline-block;
  padding: 0.25rem 0.65rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
}

.badge-university {
  background-color: #dbeafe;
  color: #1e40af;
}

.badge-commercial {
  background-color: #fef3c7;
  color: #92400e;
}

.badge-dtc {
  background-color: #f3e8ff;
  color: #6b21a8;
}

.price-tag {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--primary);
}

.price-sub {
  font-size: 0.8rem;
  color: var(--gray-medium);
  display: block;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.55rem 1rem;
  font-size: 0.9rem;
  font-weight: 600;
  border-radius: 6px;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.15s ease;
  border: none;
}

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

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

.btn-outline {
  border: 1px solid var(--border);
  background: var(--white);
  color: var(--gray-dark);
}

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

/* Sections */
.section {
  padding: 3rem 0;
}

.section-title {
  font-size: 1.85rem;
  font-weight: 800;
  color: var(--dark);
  margin-bottom: 0.5rem;
}

.section-subtitle {
  color: var(--gray-medium);
  font-size: 1.05rem;
  margin-bottom: 2rem;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}

.card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.75rem;
  box-shadow: var(--shadow);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
  text-decoration: none;
  color: inherit;
  display: flex;
  flex-direction: column;
}

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

.card h3 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 0.75rem;
}

.card p {
  color: var(--gray-dark);
  font-size: 0.95rem;
  line-height: 1.5;
  margin-bottom: 1.25rem;
  flex-grow: 1;
}

.card-link {
  color: var(--primary);
  font-weight: 700;
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

/* Detail Pages */
.detail-header {
  background: var(--white);
  border-bottom: 1px solid var(--border);
  padding: 2.5rem 0;
}

.detail-body {
  padding: 3rem 0;
}

.article-content {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 2.5rem;
  box-shadow: var(--shadow);
  max-width: 850px;
  margin: 0 auto;
}

.article-content h2 {
  font-size: 1.75rem;
  margin: 2rem 0 1rem;
  color: var(--dark);
}

.article-content h3 {
  font-size: 1.35rem;
  margin: 1.5rem 0 0.75rem;
  color: var(--dark);
}

.article-content p {
  margin-bottom: 1.25rem;
  font-size: 1.05rem;
  color: #334155;
}

.article-content ul, .article-content ol {
  margin: 0 0 1.5rem 1.5rem;
  font-size: 1.05rem;
  color: #334155;
}

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

/* Footer */
footer {
  background: #0f172a;
  color: #94a3b8;
  padding: 3.5rem 0 2rem;
  border-top: 1px solid #1e293b;
  font-size: 0.9rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  margin-bottom: 2.5rem;
}

.footer-col h4 {
  color: var(--white);
  font-size: 1rem;
  margin-bottom: 1rem;
  font-weight: 700;
}

.footer-col ul {
  list-style: none;
}

.footer-col li {
  margin-bottom: 0.5rem;
}

.footer-col a {
  color: #94a3b8;
  text-decoration: none;
}

.footer-col a:hover {
  color: var(--white);
}

.footer-bottom {
  text-align: center;
  border-top: 1px solid #1e293b;
  padding-top: 1.5rem;
  font-size: 0.85rem;
}

@media (max-width: 768px) {
  .hero h1 {
    font-size: 2rem;
  }
  .nav-container {
    flex-direction: column;
    height: auto;
    padding: 1rem 0;
    gap: 0.75rem;
  }
  nav a {
    margin: 0 0.5rem;
  }
}