/* ==========================================================================
   Design Spectrum — Core Design System & Tokens
   ========================================================================== */

:root {
  /* Color Palette — Refined Neutral Base with Restrained Accents */
  --bg-main: #f9fafb;
  --bg-card: #ffffff;
  --bg-elevated: #ffffff;
  --bg-subtle: #f3f4f6;
  --bg-dark: #111827;
  
  --text-primary: #111827;
  --text-secondary: #4b5563;
  --text-muted: #6b7280;
  --text-inverse: #f9fafb;

  --accent-primary: #2563eb;
  --accent-primary-hover: #1d4ed8;
  --accent-light: #eff6ff;
  --accent-border: #bfdbfe;
  
  --border-light: #e5e7eb;
  --border-strong: #d1d5db;
  
  --focus-ring: rgba(37, 99, 235, 0.4);
  
  /* Typography */
  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  --font-serif: 'Playfair Display', Georgia, Cambria, serif;
  --font-mono: 'JetBrains Mono', Consolas, Monaco, monospace;
  
  --fs-xs: 0.75rem;    /* 12px */
  --fs-sm: 0.875rem;   /* 14px */
  --fs-base: 1rem;     /* 16px */
  --fs-lg: 1.125rem;   /* 18px */
  --fs-xl: 1.25rem;    /* 20px */
  --fs-2xl: 1.5rem;    /* 24px */
  --fs-3xl: 1.875rem;  /* 30px */
  --fs-4xl: 2.25rem;   /* 36px */
  --fs-5xl: 3rem;      /* 48px */
  
  --fw-normal: 400;
  --fw-medium: 500;
  --fw-semibold: 600;
  --fw-bold: 700;

  /* Spacing */
  --space-1: 0.25rem;  /* 4px */
  --space-2: 0.5rem;   /* 8px */
  --space-3: 0.75rem;  /* 12px */
  --space-4: 1rem;     /* 16px */
  --space-6: 1.5rem;   /* 24px */
  --space-8: 2rem;     /* 32px */
  --space-12: 3rem;    /* 48px */
  --space-16: 4rem;    /* 64px */
  --space-20: 5rem;    /* 80px */
  
  /* Shadow Elevation */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -1px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -2px rgba(0, 0, 0, 0.03);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

  /* Border Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 220ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 300ms cubic-bezier(0.16, 1, 0.3, 1);
  
  /* Layout Max Width */
  --max-width: 1340px;
}

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

html {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-main);
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

body.modal-open {
  overflow: hidden !important;
}

/* Typography Elements */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-primary);
  font-weight: var(--fw-bold);
  line-height: 1.25;
  letter-spacing: -0.02em;
}

p {
  color: var(--text-secondary);
}

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

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

button, input, select, textarea {
  font: inherit;
  color: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
}

/* Accessibility Focus States */
:focus-visible {
  outline: 3px solid var(--accent-primary);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

.visually-hidden {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

.skip-link {
  position: absolute;
  top: -100px;
  left: 20px;
  background: var(--accent-primary);
  color: #ffffff;
  padding: var(--space-3) var(--space-6);
  z-index: 9999;
  border-radius: var(--radius-md);
  font-weight: var(--fw-semibold);
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 20px;
}

/* Container Utility */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

@media (max-width: 640px) {
  .container {
    padding: 0 var(--space-4);
  }
}