/* Accessibility utilities, animations, and back-to-top control */

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  border: 0;
  margin: -1px;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

.floating-line-link {
  position: fixed;
  right: max(24px, env(safe-area-inset-right));
  bottom: calc(max(24px, env(safe-area-inset-bottom)) + 68px);
  z-index: 900;
  display: grid;
  width: 56px;
  height: 56px;
  padding: 4px;
  place-items: center;
  border: 0;
  background: transparent;
  text-decoration: none;
}

.floating-line-link img {
  display: block;
  width: 48px;
  height: 48px;
  border-radius: 10px;
}

.back-to-top {
  position: fixed;
  right: max(24px, env(safe-area-inset-right));
  bottom: max(24px, env(safe-area-inset-bottom));
  z-index: 900;
  display: grid;
  width: 56px;
  height: 56px;
  place-items: center;
  border: 1px solid var(--color-border-bright);
  border-radius: 50%;
  background: var(--color-panel-strong);
  color: var(--color-accent-bright);
  box-shadow: 0 14px 36px rgba(22, 58, 78, 0.16);
  font-family: var(--font-tech);
  font-size: 24px;
  line-height: 1;
  opacity: 0;
  pointer-events: none;
  transform: translateY(12px);
  visibility: hidden;
  backdrop-filter: blur(14px);
  transition:
    opacity var(--transition-fast),
    transform var(--transition-fast),
    visibility 0s linear var(--duration-fast),
    border-color var(--transition-fast),
    background var(--transition-fast),
    color var(--transition-fast),
    box-shadow var(--transition-fast);
}

.back-to-top.is-visible {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
  transition-delay: 0s;
  visibility: visible;
}

.back-to-top:hover {
  border-color: var(--color-accent-bright);
  background: var(--color-accent);
  color: var(--color-on-accent);
  box-shadow: 0 16px 40px rgba(0, 119, 184, 0.2);
  transform: translateY(-3px);
}

.back-to-top:active {
  transform: translateY(0);
}

.back-to-top span {
  transform: translateY(-1px);
}

@media (max-width: 640px) {
  .floating-line-link {
      right: max(16px, env(safe-area-inset-right));
      bottom: calc(max(16px, env(safe-area-inset-bottom)) + 58px);
      width: 48px;
      height: 48px;
      padding: 3px;
    }

  .floating-line-link img {
      width: 42px;
      height: 42px;
      border-radius: 9px;
    }

  .back-to-top {
      right: max(16px, env(safe-area-inset-right));
      bottom: max(16px, env(safe-area-inset-bottom));
      width: 48px;
      height: 48px;
      font-size: 21px;
    }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto;
    transition-duration: 0.01ms;
    animation-duration: 0.01ms;
    animation-iteration-count: 1;
  }

  .back-to-top {
    transition-delay: 0s;
  }
}