/* Design Tokens & Global CSS Variables */
:root {
  /* Colors */
  --bg-dark: #0f172a;        /* Graphite slate */
  --bg-dark-card: #1e293b;   /* Slate card */
  --bg-dark-card-hover: #334155;
  --bg-light: #f8fafc;       /* Off-white */
  --bg-white: #ffffff;
  
  --text-dark: #0f172a;
  --text-light: #f8fafc;
  --text-muted-dark: #94a3b8;
  --text-muted-light: #64748b;
  
  --accent: #10b981;         /* Premium Emerald green */
  --accent-hover: #059669;
  --accent-glow: rgba(16, 185, 129, 0.25);
  --accent-light: #34d399;
  
  --border-light: #e2e8f0;
  --border-dark: #334155;
  
  /* Font Families */
  --font-heading: 'Outfit', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  
  /* Layout */
  --max-width: 1200px;
  --header-height: 80px;
  --border-radius: 12px;
  
  /* Transitions */
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  
  /* Box Shadow */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
  --shadow-glow: 0 0 20px rgba(16, 185, 129, 0.15);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  background-color: var(--bg-light);
  color: var(--text-dark);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Base Headings */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.25;
  color: var(--text-dark);
}

h1 {
  font-size: 2.5rem;
  letter-spacing: -0.025em;
}

h2 {
  font-size: 2rem;
  letter-spacing: -0.02em;
}

h3 {
  font-size: 1.5rem;
}

p {
  margin-bottom: 1.25rem;
  color: var(--text-muted-light);
}

p:last-child {
  margin-bottom: 0;
}

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

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

button, input, textarea, select {
  font-family: inherit;
  font-size: inherit;
}

ul, ol {
  list-style: none;
}

/* Grid & Flex Utilities */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

.grid {
  display: grid;
  gap: 2rem;
}

@media (min-width: 768px) {
  .grid-2 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(3, 1fr); }
}

/* Helper styles for dark sections */
.section-dark {
  background-color: var(--bg-dark);
  color: var(--text-light);
}

.section-dark h1,
.section-dark h2,
.section-dark h3 {
  color: var(--text-light);
}

.section-dark p {
  color: var(--text-muted-dark);
}

.section-padding {
  padding-top: 5rem;
  padding-bottom: 5rem;
}

@media (max-width: 768px) {
  .section-padding {
    padding-top: 3.5rem;
    padding-bottom: 3.5rem;
  }
}

.text-center { text-align: center; }
.text-accent { color: var(--accent); }