/* ============================================================
   BASE.CSS — Design tokens, CSS reset, typography
   ============================================================ */

/* ---- Custom Properties ---- */
:root {
  /* Brand Colors */
  --color-primary:         #1e3a5f;
  --color-primary-dark:    #152c47;
  --color-primary-light:   #2a4f80;
  --color-secondary:       #3b82f6;
  --color-secondary-dark:  #2563eb;
  --color-secondary-light: #60a5fa;
  --color-accent:          #0ea5e9;

  /* Neutrals */
  --color-bg:          #f8f9fb;
  --color-surface:     #ffffff;
  --color-surface-alt: #f1f4f8;
  --color-border:      #d1dce8;
  --color-text:        #1a2535;
  --color-text-muted:  #5a6a7e;
  --color-text-light:  #8a9ab0;

  /* Status */
  --color-success:     #16a34a;
  --color-error:       #dc2626;
  --color-warning:     #d97706;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;

  --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;

  --weight-regular:  400;
  --weight-medium:   500;
  --weight-semibold: 600;
  --weight-bold:     700;

  --leading-tight:   1.2;
  --leading-snug:    1.35;
  --leading-normal:  1.5;
  --leading-relaxed: 1.7;

  /* Spacing (8px base) */
  --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;

  /* Layout */
  --container-sm:  640px;
  --container-md:  768px;
  --container-lg:  1024px;
  --container-xl:  1200px;
  --container-2xl: 1400px;

  /* Borders */
  --radius-sm:   4px;
  --radius-md:   8px;
  --radius-lg:   12px;
  --radius-xl:   16px;
  --radius-2xl:  24px;
  --radius-full: 9999px;

  /* Shadows (navy-tinted) */
  --shadow-sm:  0 1px 3px rgba(30,58,95,0.08), 0 1px 2px rgba(30,58,95,0.05);
  --shadow-md:  0 4px 12px rgba(30,58,95,0.10), 0 2px 4px rgba(30,58,95,0.06);
  --shadow-lg:  0 10px 30px rgba(30,58,95,0.12), 0 4px 8px rgba(30,58,95,0.06);
  --shadow-xl:  0 20px 50px rgba(30,58,95,0.15);
  --shadow-focus: 0 0 0 3px rgba(59,130,246,0.35);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;

  /* Z-index */
  --z-below:    -1;
  --z-base:      0;
  --z-raised:    10;
  --z-dropdown:  100;
  --z-sticky:    200;
  --z-overlay:   300;

  /* Heading color (separate from primary so dark mode can flip it) */
  --color-heading: var(--color-primary);
}

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

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

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

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

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

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

ul, ol {
  list-style: none;
}

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

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

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

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

/* ---- Utility classes ---- */
.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;
}

.skip-link {
  position: absolute;
  top: var(--space-4);
  left: var(--space-4);
  padding: var(--space-2) var(--space-4);
  background: var(--color-primary);
  color: #fff;
  border-radius: var(--radius-md);
  font-weight: var(--weight-semibold);
  z-index: 9999;
  transform: translateY(-120%);
  transition: transform var(--transition-fast);
}

.skip-link:focus {
  transform: translateY(0);
}

/* Focus visible ring */
:focus-visible {
  outline: 2px solid var(--color-secondary);
  outline-offset: 2px;
}

/* ---- Scroll Reveal ---- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}

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

.reveal[data-delay="1"] { transition-delay: 0.1s; }
.reveal[data-delay="2"] { transition-delay: 0.2s; }
.reveal[data-delay="3"] { transition-delay: 0.3s; }
.reveal[data-delay="4"] { transition-delay: 0.4s; }
.reveal[data-delay="5"] { transition-delay: 0.5s; }

/* ============================================================
   COLOR THEMES — override CSS variables via data-theme on <html>
   ============================================================ */

/* Theme: Ocean — deep teal + cyan */
[data-theme="ocean"] {
  --color-primary:         #0d5c72;
  --color-primary-dark:    #094758;
  --color-primary-light:   #12748f;
  --color-secondary:       #06b6d4;
  --color-secondary-dark:  #0891b2;
  --color-secondary-light: #22d3ee;
  --color-accent:          #0ea5e9;
  --shadow-sm:   0 1px 3px rgba(13,92,114,0.08), 0 1px 2px rgba(13,92,114,0.05);
  --shadow-md:   0 4px 12px rgba(13,92,114,0.10), 0 2px 4px rgba(13,92,114,0.06);
  --shadow-lg:   0 10px 30px rgba(13,92,114,0.12), 0 4px 8px rgba(13,92,114,0.06);
  --shadow-xl:   0 20px 50px rgba(13,92,114,0.15);
  --shadow-focus: 0 0 0 3px rgba(6,182,212,0.35);
}

/* Theme: Forest — deep green + emerald */
[data-theme="forest"] {
  --color-primary:         #14532d;
  --color-primary-dark:    #0f3d20;
  --color-primary-light:   #1a6b3a;
  --color-secondary:       #16a34a;
  --color-secondary-dark:  #15803d;
  --color-secondary-light: #4ade80;
  --color-accent:          #10b981;
  --shadow-sm:   0 1px 3px rgba(20,83,45,0.08), 0 1px 2px rgba(20,83,45,0.05);
  --shadow-md:   0 4px 12px rgba(20,83,45,0.10), 0 2px 4px rgba(20,83,45,0.06);
  --shadow-lg:   0 10px 30px rgba(20,83,45,0.12), 0 4px 8px rgba(20,83,45,0.06);
  --shadow-xl:   0 20px 50px rgba(20,83,45,0.15);
  --shadow-focus: 0 0 0 3px rgba(22,163,74,0.35);
}

/* Theme: Slate — charcoal + violet */
[data-theme="slate"] {
  --color-primary:         #1e293b;
  --color-primary-dark:    #0f172a;
  --color-primary-light:   #334155;
  --color-secondary:       #8b5cf6;
  --color-secondary-dark:  #7c3aed;
  --color-secondary-light: #a78bfa;
  --color-accent:          #06b6d4;
  --shadow-sm:   0 1px 3px rgba(30,41,59,0.08), 0 1px 2px rgba(30,41,59,0.05);
  --shadow-md:   0 4px 12px rgba(30,41,59,0.10), 0 2px 4px rgba(30,41,59,0.06);
  --shadow-lg:   0 10px 30px rgba(30,41,59,0.12), 0 4px 8px rgba(30,41,59,0.06);
  --shadow-xl:   0 20px 50px rgba(30,41,59,0.15);
  --shadow-focus: 0 0 0 3px rgba(139,92,246,0.35);
}

/* Theme: Sunset — burgundy + orange */
[data-theme="sunset"] {
  --color-primary:         #7c2d12;
  --color-primary-dark:    #5c1f08;
  --color-primary-light:   #9a3c1a;
  --color-secondary:       #ea580c;
  --color-secondary-dark:  #c2410c;
  --color-secondary-light: #fb923c;
  --color-accent:          #f59e0b;
  --shadow-sm:   0 1px 3px rgba(124,45,18,0.08), 0 1px 2px rgba(124,45,18,0.05);
  --shadow-md:   0 4px 12px rgba(124,45,18,0.10), 0 2px 4px rgba(124,45,18,0.06);
  --shadow-lg:   0 10px 30px rgba(124,45,18,0.12), 0 4px 8px rgba(124,45,18,0.06);
  --shadow-xl:   0 20px 50px rgba(124,45,18,0.15);
  --shadow-focus: 0 0 0 3px rgba(234,88,12,0.35);
}

/* ============================================================
   DARK MODE — override neutrals via data-mode="dark" on <html>
   ============================================================ */
[data-mode="dark"] {
  --color-bg:          #0d1117;
  --color-surface:     #161b22;
  --color-surface-alt: #21262d;
  --color-border:      #30363d;
  --color-text:        #c9d1d9;
  --color-text-muted:  #8b949e;
  --color-text-light:  #6e7681;
  --color-heading:     #e2e8f0;
}