.article-body figure.double-slit {
  margin: 1.5rem 0;
  padding: 1rem;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--bg-surface);
  text-align: left;
}
.double-slit-toolbar { display: flex; align-items: center; justify-content: space-between; gap: 1rem; margin-bottom: .6rem; }
.double-slit-toolbar span { color: var(--text-secondary); font-size: .8rem; }
.double-slit-toolbar button {
  padding: .35rem .75rem;
  border: 1px solid var(--border-focus);
  border-radius: 6px;
  background: transparent;
  color: var(--text-primary);
  font: inherit;
  font-size: .8rem;
  cursor: pointer;
}
.double-slit-toolbar button:hover { background: var(--accent-dim); }
.double-slit-toolbar button:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
.double-slit-panels { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .8rem; }
.double-slit-panels svg { display: block; width: 100%; border-radius: 8px; background: var(--bg-base); }
.double-slit-panels text { font-family: inherit; }
.slit-heading { fill: var(--text-primary); font-size: 17px; font-weight: 600; }
.slit-label { fill: var(--text-secondary); font-size: 12px; }
.slit-screen { fill: var(--bg-elevated); stroke: var(--border-focus); }
.slit-barrier { fill: var(--text-secondary); }
.slit-source { fill: var(--accent); }
.slit-minus { fill: none; stroke: var(--bg-base); stroke-width: 1.5; }
.slit-beam { fill: none; stroke: var(--text-muted); stroke-width: 1; stroke-dasharray: 3 5; }
.slit-ray { fill: none; stroke: var(--accent); stroke-width: 1; opacity: .45; }
.slit-dots-classical { fill: var(--accent-hover); opacity: .8; }
.slit-dots-observed { fill: var(--success); opacity: .8; }
@media (max-width: 600px) {
  .double-slit-panels { grid-template-columns: 1fr; }
  .article-body figure.double-slit { padding: .65rem; }
}