/* ============================================
   World Data Foundation — Base Styles
   ============================================ */

/* --- CSS Variables --- */
:root {
  --color-navy: #0a1a3a;
  --color-navy-dark: #060f22;
  --color-white: #ffffff;
  --color-silver: #c0c8d4;
  --color-grey-bg: #f5f7fa;
  --color-accent: #4a90d9;
  --color-accent-hover: #3a7bc8;
  --color-text: #2c3e50;
  --color-text-light: #6b7c93;
  --color-border: #e1e5eb;

  --font-heading: 'Playfair Display', Georgia, serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  --max-width: 1200px;
  --nav-height: 72px;

  --transition: 0.3s ease;
}

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

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

body {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-white);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

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

a:hover {
  color: var(--color-accent-hover);
}

ul, ol {
  list-style: none;
}

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

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-navy);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

@media (min-width: 768px) {
  h1 { font-size: 3.5rem; }
  h2 { font-size: 2.5rem; }
  h3 { font-size: 1.75rem; }
}

/* --- Utilities --- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 80px 0;
}

@media (min-width: 768px) {
  .section {
    padding: 100px 0;
  }
}

.section-title {
  text-align: center;
  margin-bottom: 16px;
}

.section-subtitle {
  text-align: center;
  color: var(--color-text-light);
  font-size: 1.125rem;
  max-width: 640px;
  margin: 0 auto 48px;
}

.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;
}