/* iai-base.css — reset, design tokens, typography */

/* ===== DESIGN TOKENS ===== */
:root {
  /* Brand palette */
  --iai-brand-primary: #1C2B3A;
  --iai-brand-secondary: #243447;
  --iai-accent-amber: #D97706;
  --iai-accent-amber-aa-light: #B45309;
  --iai-accent-amber-aa-dark: #FBBF24;

  /* Foreground tokens */
  --iai-fg-light-primary: #0F1C28;
  --iai-fg-light-secondary: #3D5166;
  --iai-fg-light-muted: #637D96;
  --iai-fg-dark-primary: #E8EDF2;
  --iai-fg-dark-secondary: #A8BBC9;
  --iai-fg-dark-muted: #6B8A9E;

  /* Background tokens */
  --iai-bg-light: #F5F7F9;
  --iai-bg-white: #FFFFFF;
  --iai-bg-dark: #1C2B3A;
  --iai-bg-dark-alt: #243447;
  --iai-bg-steel-mid: #2D4155;
  --iai-bg-subtle-rule: #E2E8ED;

  /* Typography */
  --iai-font-sans: 'IBM Plex Sans', Inter, system-ui, -apple-system, sans-serif;
  --iai-font-mono: 'IBM Plex Mono', 'JetBrains Mono', 'Courier New', monospace;

  /* Type scale */
  --iai-display: 3.5rem;
  --iai-h1: 2.5rem;
  --iai-h2: 1.875rem;
  --iai-h3: 1.375rem;
  --iai-h4: 1.125rem;
  --iai-body-lg: 1.0625rem;
  --iai-body: 0.9375rem;
  --iai-label: 0.8125rem;
  --iai-mono-data: 1.5rem;
  --iai-mono-trace: 0.875rem;

  /* Spacing */
  --iai-section-y: 96px;
  --iai-container-max: 1200px;
  --iai-gutter: 24px;

  /* Radii */
  --iai-radius-card: 6px;
  --iai-radius-btn: 4px;
  --iai-radius-badge: 3px;
  --iai-radius-input: 4px;

  /* Shadows */
  --iai-shadow-card: 0 1px 3px rgba(15,28,40,0.08), 0 4px 12px rgba(15,28,40,0.06);
  --iai-shadow-card-hover: 0 4px 16px rgba(15,28,40,0.12), 0 8px 24px rgba(15,28,40,0.08);
  --iai-shadow-elevated: 0 8px 32px rgba(15,28,40,0.14);

  /* Nav height */
  --iai-nav-h: 68px;
}

/* ===== 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(--iai-font-sans);
  font-size: var(--iai-body);
  line-height: 1.65;
  color: var(--iai-fg-light-primary);
  background: var(--iai-bg-white);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

ul, ol {
  list-style: none;
}

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

/* ===== TYPOGRAPHY ===== */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--iai-font-sans);
  font-weight: 700;
  line-height: 1.2;
}

.iai-display {
  font-size: var(--iai-display);
  font-weight: 700;
  line-height: 1.10;
  letter-spacing: -0.02em;
}

h1, .iai-h1 {
  font-size: var(--iai-h1);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.015em;
}

h2, .iai-h2 {
  font-size: var(--iai-h2);
  font-weight: 600;
  line-height: 1.25;
}

h3, .iai-h3 {
  font-size: var(--iai-h3);
  font-weight: 600;
  line-height: 1.35;
}

h4, .iai-h4 {
  font-size: var(--iai-h4);
  font-weight: 600;
  line-height: 1.4;
}

.iai-body-lg {
  font-size: var(--iai-body-lg);
  line-height: 1.65;
}

.iai-label {
  font-size: var(--iai-label);
  font-weight: 500;
  line-height: 1.4;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.iai-mono-data {
  font-family: var(--iai-font-mono);
  font-size: var(--iai-mono-data);
  font-weight: 500;
}

.iai-mono-trace {
  font-family: var(--iai-font-mono);
  font-size: var(--iai-mono-trace);
  font-weight: 400;
}

/* ===== LAYOUT UTILITIES ===== */
.iai-container {
  width: 100%;
  max-width: var(--iai-container-max);
  margin: 0 auto;
  padding: 0 var(--iai-gutter);
}

.iai-section {
  padding: var(--iai-section-y) 0;
}

.iai-section--dark {
  background: var(--iai-bg-dark);
}

.iai-section--dark-alt {
  background: var(--iai-bg-dark-alt);
}

.iai-section--light {
  background: var(--iai-bg-light);
}

.iai-section--white {
  background: var(--iai-bg-white);
}

.iai-section--steel-mid {
  background: var(--iai-bg-steel-mid);
}

/* ===== EYEBROW / SECTION LABEL ===== */
.iai-eyebrow {
  font-size: var(--iai-label);
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 12px;
  display: block;
}

.iai-section--white .iai-eyebrow,
.iai-section--light .iai-eyebrow {
  color: var(--iai-accent-amber-aa-light);
}

.iai-section--dark .iai-eyebrow,
.iai-section--dark-alt .iai-eyebrow,
.iai-section--steel-mid .iai-eyebrow {
  color: var(--iai-accent-amber-aa-dark);
}

/* ===== HEADINGS IN DARK/LIGHT SECTIONS ===== */
.iai-section--dark h1,
.iai-section--dark h2,
.iai-section--dark h3,
.iai-section--dark h4,
.iai-section--dark-alt h1,
.iai-section--dark-alt h2,
.iai-section--dark-alt h3,
.iai-section--dark-alt h4,
.iai-section--steel-mid h1,
.iai-section--steel-mid h2,
.iai-section--steel-mid h3,
.iai-section--steel-mid h4 {
  color: var(--iai-fg-dark-primary);
}

.iai-section--dark p,
.iai-section--dark li,
.iai-section--dark-alt p,
.iai-section--dark-alt li,
.iai-section--steel-mid p,
.iai-section--steel-mid li {
  color: var(--iai-fg-dark-secondary);
}

.iai-section--white h1,
.iai-section--white h2,
.iai-section--white h3,
.iai-section--white h4,
.iai-section--light h1,
.iai-section--light h2,
.iai-section--light h3,
.iai-section--light h4 {
  color: var(--iai-fg-light-primary);
}

.iai-section--white p,
.iai-section--white li,
.iai-section--light p,
.iai-section--light li {
  color: var(--iai-fg-light-secondary);
}

/* ===== FADE-IN ANIMATION (with failsafe) ===== */
.iai-fade-in {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.iai-fade-in.visible {
  opacity: 1;
  transform: none;
}

/* Failsafe: force visible after 1.2s */
@keyframes iai-force-visible {
  to { opacity: 1; transform: none; }
}

.iai-fade-in {
  animation: iai-force-visible 0.01s 1.2s forwards;
}

/* ===== RESPONSIVE BREAKPOINTS ===== */
@media (max-width: 1024px) {
  :root {
    --iai-section-y: 64px;
    --iai-display: 2.75rem;
    --iai-h1: 2rem;
  }
}

@media (max-width: 768px) {
  :root {
    --iai-section-y: 48px;
    --iai-display: 2.25rem;
    --iai-h1: 1.75rem;
    --iai-h2: 1.5rem;
    --iai-gutter: 16px;
  }
}

@media (max-width: 480px) {
  :root {
    --iai-display: 1.875rem;
    --iai-h1: 1.625rem;
  }
}