/* Native circle first; floating behavior is a progressive enhancement. */
.reader-tools.tutorial-top-tools {
  display: flex;
  justify-content: flex-end;
  width: min(100% - 2rem, 56rem);
  margin: 1rem auto;
  padding: 0;
  border: 0;
  background: transparent;
}
.reader-tools.tutorial-top-tools #back-to-top {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: 0 0 auto;
  width: 48px;
  height: 48px;
  min-height: 48px;
  min-width: 48px;
  padding: 0;
  border: 2px solid rgba(255, 255, 255, 0.95);
  border-radius: 50%;
  background: linear-gradient(135deg, #123b5d 0%, #0d2840 100%);
  color: #ffffff;
  text-decoration: none;
  box-shadow: 0 4px 16px rgba(18, 59, 93, 0.3), 0 2px 6px rgba(0, 0, 0, 0.1);
  cursor: pointer;
  outline: none;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
  user-select: none;
  -webkit-user-select: none;
  transition: transform 0.22s cubic-bezier(0.16, 1, 0.3, 1),
              background 0.2s ease,
              box-shadow 0.22s cubic-bezier(0.16, 1, 0.3, 1),
              border-color 0.2s ease;
}
@media (hover: hover) and (pointer: fine) {
  .reader-tools.tutorial-top-tools #back-to-top:hover {
    transform: translateY(-3px) scale(1.06);
    background: linear-gradient(135deg, #1d4ed8 0%, #123b5d 100%);
    border-color: #bfdbfe;
    box-shadow: 0 8px 24px rgba(29, 78, 216, 0.38), 0 3px 8px rgba(0, 0, 0, 0.12);
    color: #ffffff;
  }
  .reader-tools.tutorial-top-tools #back-to-top:hover .tutorial-top-icon {
    transform: translateY(-2px);
  }
}
.reader-tools.tutorial-top-tools #back-to-top:active {
  transform: scale(0.92);
  box-shadow: 0 2px 8px rgba(18, 59, 93, 0.25);
  transition: transform 0.1s ease;
}
.reader-tools.tutorial-top-tools #back-to-top:focus-visible {
  outline: 3px solid #38bdf8;
  outline-offset: 3px;
  box-shadow: 0 0 0 4px rgba(56, 189, 248, 0.35), 0 6px 20px rgba(18, 59, 93, 0.3);
}
.tutorial-top-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  color: #ffffff;
  transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}
.reader-tools.tutorial-top-tools #back-to-top:hover .tutorial-top-icon {
  transform: translateY(-2px);
}
.tutorial-top-icon svg {
  display: block;
  width: 22px;
  height: 22px;
  stroke: #ffffff;
  stroke-width: 2.4;
}
.reader-tools.tutorial-top-tools #back-to-top > span:last-child {
  display: none !important;
}
.reader-tools.tutorial-top-tools #back-to-top small {
  display: none !important;
}

/* Floating FAB state */
.reader-tools.tutorial-top-tools.is-floating {
  position: fixed !important;
  z-index: 99 !important;
  right: max(1.5rem, env(safe-area-inset-right)) !important;
  bottom: calc(1.5rem + var(--reader-banner-space, 0px) + env(safe-area-inset-bottom)) !important;
  width: auto !important;
  margin: 0 !important;
  padding: 0 !important;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: translateY(14px) scale(0.92);
  transition: opacity 0.28s cubic-bezier(0.16, 1, 0.3, 1),
              visibility 0.28s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.28s cubic-bezier(0.16, 1, 0.3, 1);
}
.reader-tools.tutorial-top-tools.is-floating.is-visible {
  opacity: 1 !important;
  visibility: visible !important;
  pointer-events: auto !important;
  transform: translateY(0) scale(1) !important;
}
.reader-tools.tutorial-top-tools.is-floating[hidden] {
  display: none !important;
}
@media (max-width: 639px) {
  .reader-tools.tutorial-top-tools #back-to-top {
    width: 44px;
    height: 44px;
    min-height: 44px;
    min-width: 44px;
  }
  .tutorial-top-icon, .tutorial-top-icon svg {
    width: 20px;
    height: 20px;
  }
  .reader-tools.tutorial-top-tools.is-floating {
    right: max(1rem, env(safe-area-inset-right)) !important;
    bottom: calc(1rem + var(--reader-banner-space, 0px) + env(safe-area-inset-bottom)) !important;
  }
}
@media (prefers-reduced-motion: reduce) {
  .reader-tools.tutorial-top-tools.is-floating,
  .reader-tools.tutorial-top-tools #back-to-top,
  .tutorial-top-icon {
    transition: none !important;
  }
}
@media print {
  .reader-tools.tutorial-top-tools {
    display: none !important;
  }
}