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

:root {
  /* Colors */
  --color-bg: #ffffff;
  --color-bg-alt: #f5f5f7;
  --color-text: #1d1d1f;
  --color-text-secondary: #6e6e73;
  --color-accent: #2a6496;
  --color-accent-hover: #1d4e77;
  --color-border: #d2d2d7;
  --color-card-bg: #ffffff;
  --color-card-shadow: rgba(0, 0, 0, 0.08);
  --color-tag-bg: #e8eef4;
  --color-tag-text: #2a6496;
  --color-nav-bg: rgba(255, 255, 255, 0.92);
  --color-badge-bg: #fef3cd;
  --color-badge-text: #856404;

  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
  --font-size-base: 16px;
  --font-size-sm: 0.875rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;
  --font-size-3xl: 2.5rem;
  --line-height: 1.6;

  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  --spacing-section: 5rem;

  /* Layout */
  --max-width: 960px;
  --nav-height: 60px;
  --border-radius: 8px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
}

html {
  font-size: var(--font-size-base);
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-height) + var(--spacing-lg));
}

body {
  font-family: var(--font-family);
  line-height: var(--line-height);
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

ul {
  list-style: none;
}

h1,
h2,
h3,
h4 {
  line-height: 1.2;
  font-weight: 600;
}

h2 {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-xl);
}

/* Utility: container */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

/* Utility: section spacing */
.section {
  padding: var(--spacing-section) 0;
}

/* Utility: screen reader only */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}