/* ============================================
   CSS CUSTOM PROPERTIES - DESIGN TOKENS
   ============================================ */
:root {
  /* Color Palette - Professional Blue Theme */
  --color-primary-50: #e3f2fd;
  --color-primary-100: #bbdefb;
  --color-primary-200: #90caf9;
  --color-primary-300: #64b5f6;
  --color-primary-400: #42a5f5;
  --color-primary-500: #2196f3;
  --color-primary-600: #1e88e5;
  --color-primary-700: #1976d2;
  --color-primary-800: #1565c0;
  --color-primary-900: #0d47a1;

  --color-secondary-50: #f3e5f5;
  --color-secondary-100: #e1bee7;
  --color-secondary-200: #ce93d8;
  --color-secondary-300: #ba68c8;
  --color-secondary-400: #ab47bc;
  --color-secondary-500: #9c27b0;
  --color-secondary-600: #8e24aa;
  --color-secondary-700: #7b1fa2;
  --color-secondary-800: #6a1b9a;
  --color-secondary-900: #4a148c;

  --color-accent: #ff6b6b;
  --color-success: #4caf50;
  --color-warning: #ff9800;
  --color-error: #f44336;

  /* Neutral Colors */
  --color-gray-50: #fafafa;
  --color-gray-100: #f5f5f5;
  --color-gray-200: #eeeeee;
  --color-gray-300: #e0e0e0;
  --color-gray-400: #bdbdbd;
  --color-gray-500: #9e9e9e;
  --color-gray-600: #757575;
  --color-gray-700: #616161;
  --color-gray-800: #424242;
  --color-gray-900: #212121;

  --color-white: #ffffff;
  --color-black: #000000;

  /* Typography */
  --font-family-base: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-family-heading: 'Georgia', 'Times New Roman', serif;

  --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;

  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;

  /* Spacing Scale */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;

  /* Layout */
  --container-max-width: 1200px;
  --content-max-width: 65ch;
  --border-radius-sm: 0.25rem;
  --border-radius-md: 0.5rem;
  --border-radius-lg: 1rem;
  --border-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: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;

  /* Z-index Scale */
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal-backdrop: 1040;
  --z-modal: 1050;
  --z-popover: 1060;
  --z-tooltip: 1070;
}

/* ============================================
   CSS RESET & NORMALIZE
   ============================================ */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family-base);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--color-gray-900);
  background-color: var(--color-white);
  min-height: 100vh;
}

img,
picture,
video,
canvas,
svg {
  display: block;
  max-width: 100%;
  height: auto;
}

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

p,
h1,
h2,
h3,
h4,
h5,
h6 {
  overflow-wrap: break-word;
}

ul[role='list'],
ol[role='list'] {
  list-style: none;
}

/* ============================================
   ACCESSIBILITY
   ============================================ */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-primary-600);
  color: var(--color-white);
  padding: var(--space-sm) var(--space-md);
  text-decoration: none;
  z-index: var(--z-tooltip);
  border-radius: 0 0 var(--border-radius-md) 0;
  font-weight: var(--font-weight-semibold);
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 0;
  outline: 2px solid var(--color-white);
  outline-offset: 2px;
}

.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;
}

:focus-visible {
  outline: 2px solid var(--color-primary-500);
  outline-offset: 2px;
}

/* ============================================
   HEADER & NAVIGATION
   ============================================ */
header {
  background-color: var(--color-white);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  transition: box-shadow var(--transition-base);
}

nav {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: var(--space-md) var(--space-lg);
}

nav ul {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  gap: var(--space-xl);
}

nav a {
  color: var(--color-gray-700);
  text-decoration: none;
  font-weight: var(--font-weight-medium);
  font-size: var(--font-size-base);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--border-radius-md);
  transition: color var(--transition-fast), background-color var(--transition-fast);
  position: relative;
}

nav a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  width: 0;
  height: 2px;
  background-color: var(--color-primary-500);
  transition: width var(--transition-base), left var(--transition-base);
}

nav a:hover {
  color: var(--color-primary-600);
  background-color: var(--color-primary-50);
}

nav a:hover::after {
  width: 80%;
  left: 10%;
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
  background: linear-gradient(135deg, var(--color-primary-600) 0%, var(--color-secondary-600) 100%);
  color: var(--color-white);
  padding: var(--space-4xl) var(--space-lg);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url('data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><circle cx="50" cy="50" r="2" fill="rgba(255,255,255,0.1)"/></svg>');
  opacity: 0.3;
  pointer-events: none;
}

.hero > * {
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-family: var(--font-family-heading);
  font-size: var(--font-size-4xl);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  margin-bottom: var(--space-lg);
  max-width: 20ch;
  margin-left: auto;
  margin-right: auto;
}

.hero p {
  font-size: var(--font-size-lg);
  line-height: var(--line-height-relaxed);
  margin-bottom: var(--space-2xl);
  max-width: var(--content-max-width);
  margin-left: auto;
  margin-right: auto;
  opacity: 0.95;
}

/* ============================================
   CTA BUTTON
   ============================================ */
.cta-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-white);
  color: var(--color-primary-700);
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  padding: var(--space-md) var(--space-2xl);
  border-radius: var(--border-radius-full);
  text-decoration: none;
  box-shadow: var(--shadow-lg);
  transition: transform var(--transition-base), box-shadow var(--transition-base), background-color var(--transition-base);
  position: relative;
  overflow: hidden;
}

.cta-button::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background-color: var(--color-primary-50);
  transform: translate(-50%, -50%);
  transition: width var(--transition-slow), height var(--transition-slow);
}

.cta-button:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-xl);
}

.cta-button:hover::before {
  width: 300px;
  height: 300px;
}

.cta-button:active {
  transform: translateY(0);
}

/* ============================================
   FEATURES SECTION
   ============================================ */
.features {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: var(--space-4xl) var(--space-lg);
}

.features h2 {
  font-family: var(--font-family-heading);
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-bold);
  text-align: center;
  color: var(--color-gray-900);
  margin-bottom: var(--space-3xl);
  line-height: var(--line-height-tight);
}

.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-xl);
  grid-auto-rows: 1fr;
}

.feature-item {
  background-color: var(--color-white);
  border: 1px solid var(--color-gray-200);
  border-radius: var(--border-radius-lg);
  padding: var(--space-xl);
  transition: transform var(--transition-base), box-shadow var(--transition-base), border-color var(--transition-base);
  display: flex;
  flex-direction: column;
}

.feature-item:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary-300);
}

.feature-item h3 {
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-semibold);
  color: var(--color-primary-700);
  margin-bottom: var(--space-md);
  line-height: var(--line-height-tight);
}

.feature-item p {
  color: var(--color-gray-700);
  line-height: var(--line-height-relaxed);
  flex-grow: 1;
}

/* ============================================
   FOOTER
   ============================================ */
footer {
  background-color: var(--color-gray-900);
  color: var(--color-gray-300);
  padding: var(--space-2xl) var(--space-lg);
  margin-top: var(--space-4xl);
}

footer nav {
  max-width: var(--container-max-width);
  margin: 0 auto var(--space-xl);
  padding: 0;
}

footer nav ul {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-lg);
}

footer nav a {
  color: var(--color-gray-300);
  text-decoration: none;
  font-size: var(--font-size-sm);
  transition: color var(--transition-fast);
  padding: var(--space-xs) var(--space-sm);
}

footer nav a:hover {
  color: var(--color-primary-400);
}

footer p {
  text-align: center;
  font-size: var(--font-size-sm);
  color: var(--color-gray-500);
  max-width: var(--container-max-width);
  margin: 0 auto;
}

/* ============================================
   RESPONSIVE DESIGN - MOBILE FIRST
   ============================================ */

/* Tablet - 768px */
@media (min-width: 768px) {
  :root {
    --font-size-4xl: 2.75rem;
    --font-size-3xl: 2rem;
  }

  nav ul {
    gap: var(--space-2xl);
  }

  .hero {
    padding: var(--space-4xl) var(--space-xl);
  }

  .hero h1 {
    font-size: var(--font-size-5xl);
  }

  .features {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-2xl);
  }

  footer nav ul {
    gap: var(--space-xl);
  }
}

/* Desktop - 1024px and above */
@media (min-width: 1024px) {
  :root {
    --font-size-5xl: 3.5rem;
    --font-size-4xl: 3rem;
  }

  .hero {
    padding: 6rem var(--space-xl);
  }

  .features {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* ============================================
   REDUCED MOTION
   ============================================ */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ============================================
   PRINT STYLES
   ============================================ */
@media print {
  header,
  footer,
  .cta-button {
    display: none;
  }

  body {
    background: white;
    color: black;
  }

  .hero {
    background: white;
    color: black;
    padding: var(--space-lg);
  }

  .feature-item {
    page-break-inside: avoid;
    border: 1px solid black;
  }

  a {
    text-decoration: underline;
  }

  @page {
    margin: 2cm;
  }
}