/* ============================================================
   visualizers.css — Loop / Variable / Function-stack / SpotBug
   ============================================================ */

.viz {
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin: var(--space-6) 0;
}
.viz__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-5);
  background: var(--gradient-soft);
  border-bottom: 1px solid var(--color-border);
  font-family: var(--font-display);
}
.viz__select {
  padding: 6px 10px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-text);
}
.viz__stage {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 0;
  background: var(--color-bg);
}
.viz__stage--center { display: block; padding: var(--space-6); }
@media (max-width: 700px) {
  .viz__stage { grid-template-columns: 1fr; }
}
.viz__code {
  background: var(--color-code-bg);
  color: var(--color-code-text);
  padding: var(--space-4);
  font-family: var(--font-mono);
  font-size: 0.88rem;
  line-height: 1.7;
  border-right: 1px solid var(--color-border);
}
.viz__line {
  display: flex;
  gap: var(--space-3);
  padding: 2px 6px;
  border-radius: 4px;
  transition: background-color 200ms;
}
.viz__line.is-current {
  background: rgba(245, 158, 11, 0.25);
  box-shadow: inset 3px 0 0 #F59E0B;
}
.viz__ln {
  color: #64748B;
  user-select: none;
  min-width: 18px;
  text-align: right;
  font-size: 0.78rem;
  padding-top: 1px;
}
.viz__state {
  padding: var(--space-4);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}
.viz__label {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  font-weight: 700;
  margin-bottom: var(--space-2);
}
.viz__vars { min-height: 60px; }
.viz__var {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 4px 10px;
  background: var(--color-primary-soft);
  border: 1px solid var(--color-primary-light);
  border-radius: var(--radius-sm);
  margin: 2px 4px 2px 0;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  animation: vizPop 250ms ease;
}
.viz__var-name { color: var(--color-primary-dark); font-weight: 700; }
.viz__var-val { color: var(--color-text); }
.viz__var-empty { color: var(--color-text-muted); font-style: italic; font-size: 0.85rem; }
.viz__output pre {
  background: var(--color-code-bg);
  color: var(--color-code-text);
  padding: var(--space-3);
  border-radius: var(--radius-sm);
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  min-height: 60px;
  white-space: pre-wrap;
}
.viz__controls {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex-wrap: wrap;
  padding: var(--space-3) var(--space-5);
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
}
.viz__hint {
  flex: 1;
  font-size: 0.88rem;
  color: var(--color-text-muted);
  min-width: 200px;
}
.viz__hint strong { color: var(--color-primary-dark); }

@keyframes vizPop { from { transform: scale(0.85); opacity: 0; } to { transform: scale(1); opacity: 1; } }

/* Variable boxes */
.vb-grid {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  justify-content: center;
  align-items: flex-start;
  min-height: 140px;
}
.vb-box {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  border: 2.5px solid var(--color-primary);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  min-width: 100px;
  text-align: center;
  overflow: hidden;
  transition: transform 250ms ease, box-shadow 250ms ease;
}
.vb-box.is-fresh { animation: vbDrop 400ms ease; box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.25); }
.vb-box.is-changed { animation: vbFlash 500ms ease; }
.vb-box.is-ref { border-color: var(--color-accent); border-style: dashed; }
.vb-box__label {
  background: var(--color-primary);
  color: white;
  padding: 6px;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.85rem;
}
.vb-box.is-ref .vb-box__label { background: var(--color-accent); }
.vb-box__val {
  padding: var(--space-4);
  font-family: var(--font-mono);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text);
}
.vb-box__note {
  padding: 4px 8px;
  background: var(--color-surface-2);
  font-size: 0.75rem;
  color: var(--color-text-muted);
}
@keyframes vbDrop {
  from { transform: translateY(-30px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}
@keyframes vbFlash {
  0% { background: var(--color-surface); }
  40% { background: rgba(245, 158, 11, 0.35); }
  100% { background: var(--color-surface); }
}

/* Function call stack */
.fs-stack {
  display: flex;
  flex-direction: column;
  gap: 4px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 8px;
  background: var(--color-surface-2);
  min-height: 80px;
}
.fs-frame {
  padding: 8px 12px;
  background: var(--color-surface);
  border: 1px solid var(--color-primary-light);
  border-left: 4px solid var(--color-primary);
  border-radius: 4px;
  animation: vizPop 250ms ease;
  font-family: var(--font-mono);
  font-size: 0.85rem;
}
.fs-frame.is-returning { border-left-color: var(--color-success); background: rgba(16, 185, 129, 0.06); }
.fs-frame__name { font-weight: 700; color: var(--color-primary-dark); }
.fs-frame__vars { font-size: 0.78rem; color: var(--color-text-muted); margin-top: 2px; }
.fs-frame__got { font-size: 0.78rem; color: var(--color-success); margin-top: 2px; }
.fs-frame__ret { font-size: 0.78rem; color: var(--color-success); font-weight: 700; margin-top: 2px; }

/* Spot the Bug */
.spot-bug__code {
  display: flex;
  flex-direction: column;
  background: var(--color-code-bg);
  padding: var(--space-3);
}
.spot-bug__line {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: 6px 10px;
  background: transparent;
  color: var(--color-code-text);
  font-family: var(--font-mono);
  font-size: 0.88rem;
  text-align: left;
  border: 1.5px solid transparent;
  border-radius: 4px;
  cursor: pointer;
  transition: all 150ms;
  width: 100%;
}
.spot-bug__line:hover:not(:disabled) { background: rgba(255, 255, 255, 0.06); border-color: var(--color-primary-light); }
.spot-bug__line.is-correct { border-color: var(--color-success); background: rgba(16, 185, 129, 0.18); }
.spot-bug__line.is-wrong { border-color: var(--color-danger); background: rgba(239, 68, 68, 0.18); animation: shake 350ms ease; }
.spot-bug__line:disabled { cursor: default; }
.spot-bug__feedback {
  padding: var(--space-3) var(--space-5);
  font-size: 0.95rem;
  border-top: 1px solid var(--color-border);
}
.spot-bug__feedback.is-correct { background: rgba(16, 185, 129, 0.08); color: #047857; }
.spot-bug__feedback.is-wrong { background: rgba(239, 68, 68, 0.08); color: #B91C1C; }
.spot-bug__feedback:empty { display: none; }