/* ============================================
   DRAG-AND-DROP INTERACTION SYSTEM
   ============================================ */

.interaction-zone {
  margin: var(--spacing-md) 0;
  padding: var(--spacing-lg);
  background: linear-gradient(135deg, #FAFCFE 0%, #F0F4F8 100%);
  border: 2px solid var(--color-primary);
  border-radius: var(--radius-md);
  box-shadow: 0 2px 12px rgba(107, 156, 196, 0.12);
}

.interaction-label {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--color-primary);
  margin-bottom: var(--spacing-md);
  text-align: center;
}

.interaction-layout {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-lg);
  flex-wrap: wrap;
}

.interaction-arrow {
  font-size: 1.8rem;
  color: var(--color-primary);
  opacity: 0.4;
  flex-shrink: 0;
}

/* ============================================
   CARD SOURCE (HAND)
   ============================================ */

.interaction-hand {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  min-width: 100px;
}

.drag-card {
  padding: 10px 18px;
  background: white;
  border: 2px solid #B0C0D0;
  border-radius: 6px;
  font-family: 'Caveat', cursive;
  font-size: 1.2rem;
  font-weight: 700;
  color: #2A3040;
  text-align: center;
  cursor: grab;
  user-select: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease, opacity 0.3s ease;
  box-shadow: 1px 2px 4px rgba(0,0,0,0.08);
  position: relative;
}

.drag-card::before {
  content: "⠿";
  position: absolute;
  left: 6px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 0.7rem;
  color: #B0C0D0;
  font-family: sans-serif;
}

.drag-card:hover {
  transform: translateY(-2px) rotate(-1deg);
  box-shadow: 2px 4px 10px rgba(0,0,0,0.12);
  border-color: var(--color-primary);
}

.drag-card:active, .drag-card.dragging {
  cursor: grabbing;
  transform: rotate(-3deg) scale(1.05);
  box-shadow: 3px 6px 16px rgba(0,0,0,0.15);
  z-index: 10;
}

.drag-card.card-placed {
  opacity: 0;
  transform: scale(0.8);
  pointer-events: none;
}

.touch-clone {
  border: 2px solid var(--color-primary);
  background: white;
  border-radius: 6px;
  font-family: 'Caveat', cursive;
  font-size: 1.2rem;
  font-weight: 700;
  color: #2A3040;
  text-align: center;
  padding: 10px 18px;
  box-shadow: 4px 8px 20px rgba(0,0,0,0.2);
}

/* ============================================
   STACK DROP ZONE
   ============================================ */

.interaction-stack-area {
  flex-shrink: 0;
}

.interactive-stack-container {
  position: relative;
}

.stack-drop-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 5;
  border-radius: 8px;
  transition: background 0.2s ease, border-color 0.2s ease;
  border: 2px solid transparent;
}

.stack-drop-overlay.drag-over {
  background: rgba(107, 156, 196, 0.08);
  border-color: var(--color-primary);
  border-style: dashed;
}

/* Pop handle (invisible overlay on top chip) */
.stack-chip.is-top {
  cursor: grab;
  border-radius: 14px;
  z-index: 6;
  border: 2px dashed var(--color-primary);
  opacity: 0.3;
  transition: opacity 0.2s ease;
}

.stack-chip.is-top:hover {
  opacity: 0.5;
  cursor: grab;
}

/* ============================================
   DISCARD ZONE (for pop)
   ============================================ */

.interaction-discard {
  width: 100px;
  height: 100px;
  border: 2px dashed #C4889B;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s ease, border-color 0.2s ease;
}

.discard-label {
  font-family: 'Caveat', cursive;
  font-size: 0.95rem;
  color: #C4889B;
  opacity: 0.7;
}

.interaction-discard.drag-over {
  background: rgba(196, 136, 155, 0.1);
  border-color: #C4889B;
  border-style: solid;
}

/* ============================================
   FEEDBACK MESSAGES
   ============================================ */

.interaction-feedback {
  margin-top: var(--spacing-md);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  text-align: center;
  font-weight: 600;
  transition: opacity 0.3s ease;
}

.interaction-feedback.hidden {
  display: none;
}

.feedback-success {
  background: var(--color-success-light);
  color: #3D7A3D;
  border: 1px solid var(--color-success);
}

.feedback-error {
  background: #FFF8F0;
  color: #8A6A30;
  border: 1px solid #E8D4A0;
}

.feedback-complete {
  background: var(--color-primary-light);
  color: var(--color-primary);
  border: 1px solid var(--color-primary);
  font-size: 1rem;
}

/* ============================================
   RESPONSIVE
   ============================================ */

@media (max-width: 500px) {
  .interaction-layout {
    flex-direction: column;
  }
  .interaction-arrow {
    transform: rotate(90deg);
  }
  .interaction-hand {
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
  }
}

/* ============================================
   SLIDING WINDOW INTERACTION
   ============================================ */

.sw-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-md);
}

.sw-array {
  --sw-cell-size: 60px;
  --sw-cell-gap: 6px;
  display: flex;
  gap: var(--sw-cell-gap);
  position: relative;
  padding: 12px 8px;
  touch-action: pan-y;
}

.sw-cell {
  width: var(--sw-cell-size);
  height: var(--sw-cell-size);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  background: var(--color-surface);
  border: 2px solid #D0D8E0;
  transition: opacity 0.3s ease, transform 0.3s ease, border-color 0.3s ease;
  position: relative;
  z-index: 1;
}

.sw-cell-value {
  font-family: 'Caveat', cursive;
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--color-text);
  line-height: 1;
}

.sw-cell-index {
  font-family: 'Caveat', cursive;
  font-size: 0.8rem;
  color: var(--color-text-light);
  margin-top: 2px;
}

.sw-cell.sw-in-window {
  border-color: var(--color-primary);
  background: var(--color-primary-light);
  transform: translateY(-4px);
  box-shadow: 0 4px 12px rgba(107, 156, 196, 0.2);
}

.sw-cell.sw-outside {
  opacity: 0.4;
}

.sw-frame {
  position: absolute;
  top: 4px;
  height: calc(100% - 8px);
  border: 3px solid var(--color-primary);
  border-radius: 12px;
  pointer-events: none;
  z-index: 0;
  transition: left 0.35s ease;
  background: rgba(107, 156, 196, 0.04);
}

.sw-frame-label {
  position: absolute;
  top: -20px;
  left: 50%;
  transform: translateX(-50%);
  font-family: 'Caveat', cursive;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--color-primary);
  white-space: nowrap;
}

.sw-controls {
  display: flex;
  gap: var(--spacing-sm);
  align-items: center;
}

.sw-btn {
  min-width: 44px;
  padding: 8px 16px !important;
  font-size: 0.95rem;
}

.sw-info {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--spacing-md);
  width: 100%;
  max-width: 360px;
}

.sw-info-row {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: 6px;
  font-size: 0.9rem;
}

.sw-info-label {
  font-weight: 600;
  color: var(--color-text-muted);
  min-width: 90px;
}

.sw-info-value {
  font-family: 'Caveat', cursive;
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--color-text);
}

.sw-info-detail {
  font-size: 0.8rem;
  color: var(--color-text-light);
  margin-left: var(--spacing-xs);
}

.sw-info-change {
  background: #FFF8F0;
  border-radius: 6px;
  padding: 4px 10px;
  margin: 4px 0;
  justify-content: center;
}

.sw-leaving {
  color: #C4889B;
  font-weight: 700;
}

.sw-entering {
  color: var(--color-success);
  font-weight: 700;
}

.sw-info-best {
  border-top: 1px solid var(--color-border-light);
  padding-top: 6px;
  margin-top: 4px;
}

.sw-info-best .sw-info-value {
  color: var(--color-primary);
}

.sw-progress {
  text-align: center;
  font-size: 0.8rem;
  color: var(--color-text-light);
  margin-top: 6px;
}

@media (max-width: 500px) {
  .sw-array {
    --sw-cell-size: 44px;
    --sw-cell-gap: 4px;
  }
  .sw-cell-value {
    font-size: 1.2rem;
  }
}

/* ============================================
   DRAW CURVE INTERACTION
   ============================================ */

.dc-zone {
  background: linear-gradient(135deg, #FEFCFA 0%, #F8F4F0 100%) !important;
}

.dc-prompt {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--color-text);
  text-align: center;
  margin-bottom: var(--spacing-md);
  padding: var(--spacing-sm) var(--spacing-md);
  background: white;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border-light);
}

.dc-graph-wrap {
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: white;
  overflow: hidden;
}

.dc-controls {
  display: flex;
  gap: var(--spacing-sm);
  justify-content: center;
  margin-top: var(--spacing-md);
}

.dc-btn {
  min-width: 44px;
}

.dc-progress {
  text-align: center;
  font-size: 0.85rem;
  color: var(--color-text-light);
  margin-top: var(--spacing-sm);
  font-weight: 600;
}

/* ============================================
   QUEUE INTERACTION
   ============================================ */

.q-container {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

.q-array {
  display: flex;
  gap: 3px;
  position: relative;
  padding: 8px;
  background: linear-gradient(180deg, #EBF3FA 0%, #E0ECF6 100%);
  border: 2px solid #6B9CC4;
  border-radius: 8px;
}

.q-cell {
  width: 56px;
  height: 56px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  border-radius: 6px;
  background: white;
  border: 1.5px solid #D0D8E0;
  transition: background 0.3s ease, border-color 0.3s ease, transform 0.2s ease;
  position: relative;
}

.q-cell.q-filled {
  background: #F0EDF5;
  border-color: #A098C4;
}

.q-cell.q-is-front {
  border-color: #6B9CC4;
  border-width: 2.5px;
  box-shadow: 0 0 0 2px rgba(107, 156, 196, 0.2);
}

.q-cell.q-is-back {
  border-style: dashed;
  border-color: #8CB89B;
}

.q-cell-value {
  font-family: 'Caveat', cursive;
  font-size: 1.5rem;
  font-weight: 700;
  color: #2A3040;
  line-height: 1;
}

.q-cell-index {
  font-family: 'Caveat', cursive;
  font-size: 0.75rem;
  color: #8A95A8;
  margin-top: 2px;
}

.q-label {
  font-family: 'Caveat', cursive;
  font-weight: 700;
  font-size: 0.95rem;
  flex-shrink: 0;
}

.q-out-label { color: #6B9CC4; }
.q-in-label { color: #8CB89B; }

.q-hand {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  min-width: 70px;
}

.q-drop-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 5;
  border-radius: 6px;
  transition: background 0.2s ease;
  border: 2px solid transparent;
}

.q-drop-overlay.drag-over {
  background: rgba(140, 184, 155, 0.12);
  border-color: #8CB89B;
  border-style: dashed;
}

.q-front-cell {
  cursor: grab;
}

.q-drag-handle {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  cursor: grab;
  z-index: 6;
  border: 2px dashed #6B9CC4;
  border-radius: 6px;
  opacity: 0.3;
  transition: opacity 0.2s ease;
}

.q-drag-handle:hover {
  opacity: 0.5;
}

.q-pointers {
  display: flex;
  gap: var(--spacing-lg);
  justify-content: center;
  margin-top: var(--spacing-sm);
}

.q-ptr {
  font-family: 'Caveat', cursive;
  font-size: 0.95rem;
  font-weight: 700;
  padding: 2px 10px;
  border-radius: 4px;
}

.q-ptr-front {
  color: #6B9CC4;
  background: rgba(107, 156, 196, 0.1);
}

.q-ptr-back, .q-ptr-size {
  color: #8CB89B;
  background: rgba(140, 184, 155, 0.1);
}

/* ============================================
   SORTING SWAP INTERACTION
   ============================================ */

.ss-container {
  display: flex;
  justify-content: center;
}

.ss-array {
  display: flex;
  gap: 8px;
  padding: 12px;
}

.ss-cell {
  width: 64px;
  height: 72px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  background: white;
  border: 2px solid #D0D8E0;
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.2s ease;
  position: relative;
  user-select: none;
}

.ss-cell.ss-swappable {
  border-color: #E8785A;
  background: #FFF8F4;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(232, 120, 90, 0.15);
}

.ss-cell.ss-swappable:hover {
  transform: translateY(-4px);
  box-shadow: 0 4px 14px rgba(232, 120, 90, 0.25);
}

.ss-cell.ss-selected {
  border-color: #D4B86A;
  background: #FFF8E0;
  transform: translateY(-6px) scale(1.05);
  box-shadow: 0 6px 18px rgba(212, 184, 106, 0.3);
}

.ss-cell.ss-swapped {
  border-color: #8CB89B;
  background: #EDF5F0;
}

.ss-cell-value {
  font-family: 'Caveat', cursive;
  font-size: 1.8rem;
  font-weight: 700;
  color: #2A3040;
  line-height: 1;
}

.ss-cell-index {
  font-family: 'Caveat', cursive;
  font-size: 0.8rem;
  color: #8A95A8;
  margin-top: 4px;
}

/* ============================================
   REDUCED MOTION
   ============================================ */

@media (prefers-reduced-motion: reduce) {
  .drag-card,
  .drag-card:hover,
  .drag-card:active,
  .drag-card.card-placed,
  .ss-cell,
  .ss-cell.ss-swappable,
  .ss-cell.ss-selected {
    transition: none;
    transform: none;
  }
}

@media (max-width: 500px) {
  .q-container {
    flex-direction: column;
  }
  .q-cell {
    width: 44px;
    height: 44px;
  }
  .q-cell-value { font-size: 1.2rem; }
  .ss-cell {
    width: 50px;
    height: 58px;
  }
  .ss-cell-value { font-size: 1.4rem; }
}