/* ============================================
   TractBuilder Marketing Site - Modern CSS
   ============================================ */

/* CSS Variables (Design System) */
:root {
  /* Colors */
  --color-primary: #2563eb;
  --color-primary-dark: #1e40af;
  --color-primary-light: #3b82f6;
  --color-secondary: #059669;
  --color-secondary-dark: #047857;
  --color-accent: #f59e0b;
  --color-text: #1f2937;
  --color-text-light: #6b7280;
  --color-background: #ffffff;
  --color-background-alt: #f9fafb;
  --color-border: #e5e7eb;
  --color-error: #dc2626;
  --color-success: #059669;
  
  /* Typography */
  --font-primary: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'Courier New', Courier, monospace;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  
  /* Layout */
  --max-width-sm: 640px;
  --max-width-md: 768px;
  --max-width-lg: 1024px;
  --max-width-xl: 1280px;
  --max-width-2xl: 1536px;
  
  /* Effects */
  --border-radius: 0.375rem;
  --border-radius-lg: 0.5rem;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
  --shadow-md: 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);
  --transition: all 0.2s ease;
}

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-primary);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-background);
}

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

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

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

a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: var(--border-radius);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: var(--spacing-md);
  color: var(--color-text);
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }
h6 { font-size: var(--font-size-lg); }

p {
  margin-bottom: var(--spacing-md);
  color: var(--color-text-light);
}

/* Layout Utilities */
.container {
  width: 100%;
  max-width: var(--max-width-xl);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.container-narrow {
  max-width: var(--max-width-lg);
}

.section {
  padding: var(--spacing-3xl) 0;
}

.section-alt {
  background-color: var(--color-background-alt);
}

/* Header & Navigation */
.header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: var(--color-background);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-lg) 0;
  gap: var(--spacing-lg);
}

.nav-logo {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--color-primary);
  white-space: nowrap;
  flex-shrink: 0;
}

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

.nav-link {
  font-weight: 600;
  color: var(--color-text);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius);
  white-space: nowrap;
}

.nav-link:hover {
  color: var(--color-primary);
  background-color: var(--color-background-alt);
}

.nav-link.active {
  color: var(--color-primary);
  background-color: var(--color-background-alt);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-sm);
  flex-shrink: 0;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text);
  transition: var(--transition);
}

/* Mobile Navigation */
@media (max-width: 768px) {
  .nav-toggle {
    display: flex;
  }
  
  .nav-links {
    position: fixed;
    top: 73px;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background-color: var(--color-background);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-md);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
  }
  
  .nav-links.active {
    max-height: 400px;
  }
  
  .nav-link {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--color-border);
    width: 100%;
  }
}

/* Tablet breakpoint for navigation */
@media (min-width: 769px) and (max-width: 1100px) {
  .nav-links {
    gap: var(--spacing-sm);
  }
  
  .nav-link {
    padding: var(--spacing-sm) var(--spacing-sm);
    font-size: var(--font-size-sm);
  }
}

/* Hero Section */
.hero {
  padding: var(--spacing-3xl) 0;
  text-align: center;
  background: linear-gradient(135deg, #2563eb 0%, #1e40af 100%);
  color: white;
}

.hero h1 {
  color: white;
  margin-bottom: var(--spacing-lg);
}

.hero p {
  font-size: var(--font-size-xl);
  color: rgba(255, 255, 255, 0.9);
  margin-bottom: var(--spacing-xl);
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
}

.hero-cta {
  display: flex;
  gap: var(--spacing-lg);
  justify-content: center;
  flex-wrap: wrap;
  margin-top: var(--spacing-2xl);
}

/* Buttons */
.btn {
  display: inline-block;
  padding: var(--spacing-md) var(--spacing-xl);
  font-weight: 600;
  border-radius: var(--border-radius-lg);
  border: none;
  cursor: pointer;
  transition: var(--transition);
  text-align: center;
  font-size: var(--font-size-base);
}

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

.btn-primary:hover {
  background-color: var(--color-primary-dark);
  color: white;
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

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

.btn-secondary:hover {
  background-color: var(--color-secondary-dark);
  color: white;
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-outline {
  background-color: transparent;
  color: white;
  border: 2px solid white;
}

.btn-outline:hover {
  background-color: white;
  color: var(--color-primary);
  transform: translateY(-2px);
}

.btn-lg {
  padding: var(--spacing-lg) var(--spacing-2xl);
  font-size: var(--font-size-lg);
}

/* Feature Grid */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-2xl);
  margin-top: var(--spacing-2xl);
}

.feature-card {
  padding: var(--spacing-xl);
  background-color: var(--color-background);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-lg);
  transition: var(--transition);
}

.feature-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
}

.feature-icon {
  width: 48px;
  height: 48px;
  background-color: var(--color-primary-light);
  color: white;
  border-radius: var(--border-radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-lg);
}

.feature-card h3 {
  margin-bottom: var(--spacing-md);
  color: var(--color-text);
}

.feature-card p {
  color: var(--color-text-light);
  margin-bottom: 0;
}

/* Downloads List */
.download-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
  margin-top: var(--spacing-2xl);
}

.download-item {
  padding: var(--spacing-lg);
  background-color: var(--color-background);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--spacing-lg);
  transition: var(--transition);
}

.download-item:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
}

.download-info h3 {
  margin-bottom: var(--spacing-sm);
  font-size: var(--font-size-lg);
}

.download-info p {
  margin-bottom: var(--spacing-sm);
  font-size: var(--font-size-sm);
}

.download-version {
  display: inline-block;
  padding: var(--spacing-xs) var(--spacing-sm);
  background-color: var(--color-background-alt);
  border-radius: var(--border-radius);
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: var(--color-text-light);
}

/* Form Styles */
.form-group {
  margin-bottom: var(--spacing-lg);
}

.form-label {
  display: block;
  margin-bottom: var(--spacing-sm);
  font-weight: 600;
  color: var(--color-text);
}

.form-input,
.form-textarea {
  width: 100%;
  padding: var(--spacing-md);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  font-family: var(--font-primary);
  font-size: var(--font-size-base);
  transition: var(--transition);
}

.form-input:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-textarea {
  resize: vertical;
  min-height: 120px;
}

/* Footer */
.footer {
  background-color: var(--color-text);
  color: rgba(255, 255, 255, 0.8);
  padding: var(--spacing-3xl) 0 var(--spacing-xl);
  margin-top: var(--spacing-3xl);
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-2xl);
  margin-bottom: var(--spacing-2xl);
}

.footer-section h4 {
  color: white;
  margin-bottom: var(--spacing-lg);
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.footer-links a {
  color: rgba(255, 255, 255, 0.8);
}

.footer-links a:hover {
  color: white;
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: var(--spacing-lg);
  text-align: center;
  color: rgba(255, 255, 255, 0.6);
  font-size: var(--font-size-sm);
}

/* Utility Classes */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }
.mt-2xl { margin-top: var(--spacing-2xl); }

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }
.mb-2xl { margin-bottom: var(--spacing-2xl); }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.gap-md { gap: var(--spacing-md); }
.gap-lg { gap: var(--spacing-lg); }

/* Responsive Typography */
@media (max-width: 768px) {
  h1 { font-size: var(--font-size-4xl); }
  h2 { font-size: var(--font-size-3xl); }
  h3 { font-size: var(--font-size-2xl); }
  
  .hero p {
    font-size: var(--font-size-lg);
  }
  
  .hero-cta {
    flex-direction: column;
  }
  
  .btn-lg {
    width: 100%;
  }
}

/* Accessibility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* Skip to main content link */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-primary);
  color: white;
  padding: var(--spacing-md);
  z-index: 100;
}

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

/* Loading State */
.loading {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 3px solid rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  border-top-color: white;
  animation: spin 0.6s linear infinite;
}

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

/* Print Styles */
@media print {
  .header, .footer, .nav-toggle, .btn { display: none; }
  body { color: black; background: white; }
  a { text-decoration: underline; }
}