/* Accessibility helpers: focus ring, skip link, hidden text, reduced motion. */

/* A clear focus ring for keyboard users.
   :focus-visible shows it for the keyboard but not for mouse clicks. */
:focus-visible {
  outline: 3px solid var(--color-focus);
  outline-offset: 2px;
}

/* The sticky header must not cover a link target or the focused element.
   The bottom value does the same for the fixed "back to top" button:
   when Tab scrolls to a link, the link stops above the button, not under it. */
html {
  scroll-padding-top: calc(var(--header-height) + var(--space-4));
  scroll-padding-bottom: 5rem;
}

/* Hidden on screen, but still read by screen readers. */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

/* The skip link is the first thing a keyboard user reaches.
   It stays above the screen until it gets focus. */
.skip-link {
  position: absolute;
  top: var(--space-3);
  left: var(--space-4);
  z-index: 100;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-sm);
  background: var(--color-text);
  color: var(--color-bg);
  font-weight: 600;
  transform: translateY(-300%);
}

.skip-link:hover {
  color: var(--color-bg);
}

.skip-link:focus {
  transform: translateY(0);
}

/* Smooth scrolling only for people who did not ask for less motion. */
@media (prefers-reduced-motion: no-preference) {
  html {
    scroll-behavior: smooth;
  }
}

/* People who ask for less motion get (almost) no animation at all.
   !important is fine here: this rule must beat every other animation. */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}