/* ============================================
   BASE STYLES
   carbotrace.in | css/base.css
   ============================================ */

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

body {
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

/* ------------------------------------------------------------------ */
/*  Headings                                                           */
/* ------------------------------------------------------------------ */

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: var(--weight-normal);
  letter-spacing: var(--tracking-tight);
  color: var(--color-text);
  line-height: var(--leading-tight);
}

/* ------------------------------------------------------------------ */
/*  Inline elements                                                    */
/* ------------------------------------------------------------------ */

a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

strong, b {
  font-weight: var(--weight-semibold);
}

/* ------------------------------------------------------------------ */
/*  Paragraphs                                                         */
/* ------------------------------------------------------------------ */

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

/* ------------------------------------------------------------------ */
/*  Layout utilities                                                   */
/* ------------------------------------------------------------------ */

.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-padding);
}

.container--narrow {
  max-width: var(--container-narrow);
}

.section {
  padding-block: var(--space-24);
}

.section--lg {
  padding-block: var(--space-32);
}

.section--sm {
  padding-block: var(--space-16);
}

/* ------------------------------------------------------------------ */
/*  Accessibility utilities                                            */
/* ------------------------------------------------------------------ */

/* Visually hidden but accessible to 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;
}

/* Skip navigation link — visible on keyboard focus */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-4);
  z-index: var(--z-modal);
  padding: var(--space-3) var(--space-6);
  background: var(--color-primary);
  color: var(--color-text-inverse);
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  text-decoration: none;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 0;
  outline: none;
}

/* ------------------------------------------------------------------ */
/*  Scroll animation                                                   */
/* ------------------------------------------------------------------ */

.animate-in {
  opacity: 0;
  transform: translateY(28px);
  transition:
    opacity var(--transition-slow),
    transform var(--transition-slow);
}

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

/* Stagger delays for grid children */
.animate-in[data-delay="1"] { transition-delay: 100ms; }
.animate-in[data-delay="2"] { transition-delay: 200ms; }
.animate-in[data-delay="3"] { transition-delay: 300ms; }
.animate-in[data-delay="4"] { transition-delay: 400ms; }

/* ------------------------------------------------------------------ */
/*  Responsive adjustments                                             */
/* ------------------------------------------------------------------ */

@media (max-width: 768px) {
  .section {
    padding-block: var(--space-16);
  }

  .section--lg {
    padding-block: var(--space-20);
  }

  .container {
    padding-inline: var(--space-4);
  }
}