/* ============================================
   Base — Reset, Typography, Layout Primitives
   ============================================ */

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

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

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--transition-base), color var(--transition-base);
  overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  line-height: 1.2;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

h1 { font-size: clamp(2rem, 5vw, 3.5rem); }
h2 { font-size: clamp(1.5rem, 3.5vw, 2.5rem); }
h3 { font-size: clamp(1.2rem, 2.5vw, 1.75rem); }
h4 { font-size: 1.25rem; }

p {
  color: var(--text-secondary);
  max-width: 65ch;
}

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

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

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

code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--bg-glass);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
}

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

.section {
  padding: 80px 0;
}

.section-sm {
  padding: 48px 0;
}

/* Utility classes */
.text-center { text-align: center; }
.text-muted { color: var(--text-muted); }
.text-accent { color: var(--accent-text); }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-sm { gap: 8px; }
.gap-md { gap: 16px; }
.gap-lg { gap: 24px; }
.gap-xl { gap: 40px; }

.grid {
  display: grid;
  gap: 24px;
}

.grid-2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }

/* Selection */
::selection {
  background: var(--accent-muted);
  color: var(--text-primary);
}

/* Scrollbar (dark mode) */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
  background: var(--border-hover);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* Focus states */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* Visually hidden (for screen readers) */
.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;
}

/* Responsive */
@media (max-width: 768px) {
  .container {
    padding: 0 16px;
  }

  .section {
    padding: 48px 0;
  }

  .grid-3 {
    grid-template-columns: 1fr;
  }
}