/* ============================================
   CSS Variables & Design Tokens
   ============================================ */
:root {
  /* Color Palette */
  --color-primary: #2563eb;
  --color-primary-dark: #1e40af;
  --color-primary-light: #3b82f6;
  --color-secondary: #64748b;
  --color-accent: #8b5cf6;

  /* Neutral Colors */
  --color-text: #1e293b;
  --color-text-light: #475569;
  --color-text-muted: #94a3b8;
  --color-background: #ffffff;
  --color-surface: #f8fafc;
  --color-border: #e2e8f0;

  /* Semantic Colors */
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-error: #ef4444;

  /* Typography */
  --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
  --font-mono: 'Monaco', 'Courier New', 'Courier', monospace;

  /* Font Sizes */
  --text-xs: 0.75rem;      /* 12px */
  --text-sm: 0.875rem;     /* 14px */
  --text-base: 1rem;       /* 16px */
  --text-lg: 1.125rem;     /* 18px */
  --text-xl: 1.25rem;      /* 20px */
  --text-2xl: 1.5rem;      /* 24px */
  --text-3xl: 1.875rem;    /* 30px */
  --text-4xl: 2.25rem;     /* 36px */
  --text-5xl: 3rem;        /* 48px */

  /* Font Weights */
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;

  /* Line Heights */
  --leading-tight: 1.25;
  --leading-snug: 1.375;
  --leading-normal: 1.5;
  --leading-relaxed: 1.625;
  --leading-loose: 2;

  /* Spacing Scale */
  --spacing-xs: 0.5rem;    /* 8px */
  --spacing-sm: 1rem;      /* 16px */
  --spacing-md: 1.5rem;    /* 24px */
  --spacing-lg: 2rem;      /* 32px */
  --spacing-xl: 3rem;      /* 48px */
  --spacing-2xl: 4rem;     /* 64px */
  --spacing-3xl: 6rem;     /* 96px */

  /* Border Radius */
  --radius-sm: 0.25rem;    /* 4px */
  --radius-md: 0.5rem;     /* 8px */
  --radius-lg: 0.75rem;    /* 12px */
  --radius-xl: 1rem;       /* 16px */
  --radius-full: 9999px;

  /* Shadows */
  --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 -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 200ms ease-in-out;
  --transition-slow: 300ms ease-in-out;

  /* Breakpoints (for reference in media queries) */
  --breakpoint-mobile: 768px;
  --breakpoint-tablet: 1024px;
  --breakpoint-desktop: 1280px;

  /* Container */
  --container-max-width: 1200px;
  --container-padding: var(--spacing-md);
}

/* ============================================
   CSS Reset & Base Styles
   ============================================ */

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

/* Document defaults */
html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-primary);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--color-text);
  background-color: var(--color-background);
}

/* Typography defaults */
h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-weight: var(--font-bold);
  line-height: var(--leading-tight);
  color: var(--color-text);
}

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

p {
  margin: 0;
  line-height: var(--leading-relaxed);
}

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

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

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

/* List reset */
ul, ol {
  list-style: none;
  margin: 0;
  padding: 0;
}

/* Image defaults */
img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Button reset */
button {
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
  cursor: pointer;
  border: none;
  background: none;
  padding: 0;
}

/* Form element defaults */
input, textarea, select {
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
  color: inherit;
}

/* Code blocks */
code, pre {
  font-family: var(--font-mono);
  font-size: 0.875em;
}

pre {
  overflow-x: auto;
  background-color: var(--color-surface);
  padding: var(--spacing-sm);
  border-radius: var(--radius-md);
}

code {
  background-color: var(--color-surface);
  padding: 0.2em 0.4em;
  border-radius: var(--radius-sm);
}

pre code {
  background-color: transparent;
  padding: 0;
}

/* Table defaults */
table {
  border-collapse: collapse;
  width: 100%;
}

/* ============================================
   Utility Classes
   ============================================ */

/* Container */
.container {
  width: 100%;
  max-width: var(--container-max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--container-padding);
  padding-right: var(--container-padding);
}

/* Text utilities */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.text-muted { color: var(--color-text-muted); }
.text-light { color: var(--color-text-light); }

/* Display utilities */
.hidden { display: none; }
.block { display: block; }
.inline-block { display: inline-block; }
.flex { display: flex; }
.inline-flex { display: inline-flex; }
.grid { display: grid; }

/* Visibility utilities */
.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;
}

/* Spacing utilities */
.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); }

.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); }

.my-sm { margin-top: var(--spacing-sm); margin-bottom: var(--spacing-sm); }
.my-md { margin-top: var(--spacing-md); margin-bottom: var(--spacing-md); }
.my-lg { margin-top: var(--spacing-lg); margin-bottom: var(--spacing-lg); }

.mx-auto { margin-left: auto; margin-right: auto; }

/* ============================================
   Responsive Typography
   ============================================ */

@media (max-width: 768px) {
  :root {
    --text-4xl: 2rem;      /* 32px on mobile */
    --text-3xl: 1.5rem;    /* 24px on mobile */
    --text-2xl: 1.25rem;   /* 20px on mobile */
  }

  .container {
    --container-padding: var(--spacing-sm);
  }
}

/* ============================================
   Selection & Focus Styles
   ============================================ */

::selection {
  background-color: var(--color-primary-light);
  color: var(--color-background);
}

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

/* ============================================
   Print Styles
   ============================================ */

@media print {
  body {
    background: white;
    color: black;
  }

  a {
    text-decoration: underline;
  }

  .no-print {
    display: none !important;
  }
}