/* ============================================
   BASE.CSS — Reset, Variables, Typography, Utilities
   ============================================ */

/* ---- Custom Properties ---- */
:root {
  /* Colors */
  --color-primary:       #1a56db;
  --color-primary-dark:  #1e429f;
  --color-primary-light: #e8f0fe;
  --color-accent:        #f59e0b;
  --color-accent-dark:   #d97706;
  --color-accent-light:  #fef3c7;
  --color-success:       #10b981;
  --color-danger:        #ef4444;

  --color-bg:            #f8fafc;
  --color-surface:       #ffffff;
  --color-surface-alt:   #f1f5f9;
  --color-border:        #e5e7eb;
  --color-border-dark:   #d1d5db;

  --color-text:          #111827;
  --color-text-muted:    #6b7280;
  --color-text-light:    #9ca3af;
  --color-text-inverse:  #ffffff;

  /* Typography */
  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;

  --text-xs:   0.75rem;
  --text-sm:   0.875rem;
  --text-base: 1rem;
  --text-lg:   1.125rem;
  --text-xl:   1.25rem;
  --text-2xl:  1.5rem;
  --text-3xl:  1.875rem;
  --text-4xl:  2.25rem;
  --text-5xl:  3rem;
  --text-6xl:  3.75rem;

  --font-normal:   400;
  --font-medium:   500;
  --font-semibold: 600;
  --font-bold:     700;
  --font-extrabold:800;

  --leading-tight:  1.25;
  --leading-snug:   1.375;
  --leading-normal: 1.5;
  --leading-relaxed:1.625;
  --leading-loose:  2;

  /* Spacing */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-14: 3.5rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  --space-32: 8rem;

  /* Borders */
  --radius-sm:   0.25rem;
  --radius-md:   0.5rem;
  --radius-lg:   0.75rem;
  --radius-xl:   1rem;
  --radius-2xl:  1.5rem;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.04);
  --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);
  --shadow-2xl:0 25px 50px -12px rgba(0,0,0,0.25);

  /* Transitions */
  --transition-fast:   150ms cubic-bezier(0.4,0,0.2,1);
  --transition-base:   250ms cubic-bezier(0.4,0,0.2,1);
  --transition-slow:   400ms cubic-bezier(0.4,0,0.2,1);

  /* Layout */
  --navbar-height:   4rem;
  --container-max:   1200px;
  --container-pad:   1.25rem;
  --section-pad-y:   5rem;
  --section-pad-y-sm:3rem;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-relaxed);
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

img, video, svg {
  display: block;
  max-width: 100%;
}

img { height: auto; }

a {
  color: inherit;
  text-decoration: none;
}

ul, ol { list-style: none; }

button {
  cursor: pointer;
  font-family: inherit;
  border: none;
  background: none;
}

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

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

p { max-width: 68ch; }

/* ---- Typography Scale ---- */
.text-xs    { font-size: var(--text-xs); }
.text-sm    { font-size: var(--text-sm); }
.text-base  { font-size: var(--text-base); }
.text-lg    { font-size: var(--text-lg); }
.text-xl    { font-size: var(--text-xl); }
.text-2xl   { font-size: var(--text-2xl); }
.text-3xl   { font-size: var(--text-3xl); }
.text-4xl   { font-size: var(--text-4xl); }
.text-5xl   { font-size: var(--text-5xl); }
.text-6xl   { font-size: var(--text-6xl); }

.font-medium   { font-weight: var(--font-medium); }
.font-semibold { font-weight: var(--font-semibold); }
.font-bold     { font-weight: var(--font-bold); }
.font-extrabold{ font-weight: var(--font-extrabold); }

.text-muted   { color: var(--color-text-muted); }
.text-primary { color: var(--color-primary); }
.text-accent  { color: var(--color-accent-dark); }
.text-success { color: var(--color-success); }
.text-center  { text-align: center; }
.text-left    { text-align: left; }
.text-right   { text-align: right; }

.leading-tight   { line-height: var(--leading-tight); }
.leading-relaxed { line-height: var(--leading-relaxed); }

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

.container--narrow {
  max-width: 760px;
}

.section {
  padding-top: var(--section-pad-y-sm);
  padding-bottom: var(--section-pad-y-sm);
}

@media (min-width: 768px) {
  :root {
    --container-pad: 2rem;
  }
  .section {
    padding-top: var(--section-pad-y);
    padding-bottom: var(--section-pad-y);
  }
}

@media (min-width: 1024px) {
  :root {
    --container-pad: 3rem;
  }
}

/* ---- Flexbox & Grid Utilities ---- */
.flex          { display: flex; }
.flex-col      { flex-direction: column; }
.flex-wrap     { flex-wrap: wrap; }
.items-center  { align-items: center; }
.items-start   { align-items: flex-start; }
.justify-center{ justify-content: center; }
.justify-between{justify-content: space-between; }
.gap-2  { gap: var(--space-2); }
.gap-4  { gap: var(--space-4); }
.gap-6  { gap: var(--space-6); }
.gap-8  { gap: var(--space-8); }

.grid       { display: grid; }
.grid-2     { grid-template-columns: repeat(2, 1fr); }
.grid-3     { grid-template-columns: repeat(3, 1fr); }
.grid-4     { grid-template-columns: repeat(4, 1fr); }

/* ---- Spacing Utilities ---- */
.mt-2  { margin-top: var(--space-2); }
.mt-4  { margin-top: var(--space-4); }
.mt-6  { margin-top: var(--space-6); }
.mt-8  { margin-top: var(--space-8); }
.mb-2  { margin-bottom: var(--space-2); }
.mb-4  { margin-bottom: var(--space-4); }
.mb-6  { margin-bottom: var(--space-6); }
.mb-8  { margin-bottom: var(--space-8); }
.mx-auto { margin-left: auto; margin-right: auto; }

/* ---- Color Utilities ---- */
.bg-white    { background-color: var(--color-surface); }
.bg-light    { background-color: var(--color-bg); }
.bg-alt      { background-color: var(--color-surface-alt); }
.bg-primary  { background-color: var(--color-primary); }
.bg-dark     { background-color: var(--color-text); }

/* ---- Section Header Pattern ---- */
.section-label {
  display: inline-block;
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-3);
}

.section-title {
  font-size: var(--text-3xl);
  font-weight: var(--font-extrabold);
  color: var(--color-text);
  margin-bottom: var(--space-4);
}

.section-subtitle {
  font-size: var(--text-lg);
  color: var(--color-text-muted);
  line-height: var(--leading-relaxed);
  max-width: 60ch;
}

.section-header {
  margin-bottom: var(--space-12);
}

.section-header--center {
  text-align: center;
}

.section-header--center .section-subtitle {
  margin-left: auto;
  margin-right: auto;
}

@media (min-width: 768px) {
  .section-title { font-size: var(--text-4xl); }
}

/* ---- Scroll Reveal Animation ---- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.reveal.revealed {
  opacity: 1;
  transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 100ms; }
.reveal-delay-2 { transition-delay: 200ms; }
.reveal-delay-3 { transition-delay: 300ms; }
.reveal-delay-4 { transition-delay: 400ms; }
.reveal-delay-5 { transition-delay: 500ms; }

/* ---- Visually Hidden (a11y) ---- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

/* ---- Skip Link ---- */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-4);
  z-index: 9999;
  padding: var(--space-2) var(--space-4);
  background: var(--color-primary);
  color: #fff;
  border-radius: var(--radius-md);
  font-weight: var(--font-semibold);
  transition: top var(--transition-fast);
}
.skip-link:focus { top: var(--space-4); }

/* ---- Divider ---- */
.divider {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--space-8) 0;
}

/* ---- Badge ---- */
.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: var(--font-semibold);
}

.badge--primary {
  background: var(--color-primary-light);
  color: var(--color-primary-dark);
}

.badge--success {
  background: #d1fae5;
  color: #065f46;
}

.badge--accent {
  background: var(--color-accent-light);
  color: #92400e;
}