/* Progressive learning aids for research articles. */

.research-learning {
  margin: var(--space-6) 0;
  padding: clamp(var(--space-4), 4vw, var(--space-6));
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--panel-2);
}

.research-learning[hidden] {
  display: none;
}

.research-learning__fallback {
  margin: var(--space-4) 0 var(--space-6);
  padding: var(--space-4);
  border-left: 4px solid var(--accent);
  background: var(--accent-soft);
  color: var(--fg);
  line-height: 1.55;
}

.research-learning__jump {
  font-weight: 700;
}

.research-learning__eyebrow {
  margin: 0 0 var(--space-1);
  color: var(--accent-text);
  font-size: var(--text-xs);
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.research-learning h2,
.research-learning h3 {
  margin: 0 0 var(--space-2);
}

.research-learning__intro {
  max-width: var(--measure);
  margin: 0 0 var(--space-4);
  color: var(--muted);
  line-height: 1.55;
}

.research-learning__controls {
  display: grid;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

.research-learning label {
  color: var(--fg);
  font-weight: 700;
}

.research-learning select,
.research-learning button {
  min-height: 44px;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--panel);
  color: var(--fg);
  font: inherit;
}

.research-learning select {
  width: min(100%, 32rem);
  padding: var(--space-2) var(--space-3);
}

.research-learning button {
  padding: var(--space-2) var(--space-4);
  cursor: pointer;
  font-weight: 700;
}

.research-learning button:hover,
.research-learning button:focus-visible,
.research-learning select:focus-visible {
  border-color: var(--accent);
  outline: 3px solid color-mix(in srgb, var(--accent) 28%, transparent);
  outline-offset: 2px;
}

.research-learning__choices {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

.research-learning__choices button[aria-pressed="true"] {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.research-learning__result {
  padding: var(--space-4);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--panel);
}

.research-learning__result p {
  max-width: var(--measure);
  margin: 0 0 var(--space-2);
  line-height: 1.55;
}

.research-learning__result p:last-child {
  margin-bottom: 0;
}

.research-learning__answer {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 800;
}

.research-learning__track {
  height: 0.75rem;
  margin-top: var(--space-3);
  overflow: hidden;
  border-radius: 999px;
  background: var(--border);
}

.research-learning__fill {
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: var(--accent);
  transition: width 180ms ease-out;
}

.sound-ladder {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: var(--space-2);
  margin: var(--space-4) 0;
  padding: 0;
  list-style: none;
}

.sound-ladder li {
  padding: var(--space-3) var(--space-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--panel);
  text-align: center;
}

.sound-ladder li[aria-current="step"] {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.sound-ladder strong,
.sound-ladder span {
  display: block;
}

.sound-ladder span {
  margin-top: var(--space-1);
  color: var(--muted);
  font-size: var(--text-xs);
}

.learning-steps {
  display: grid;
  gap: var(--space-3);
  margin: var(--space-4) 0;
  padding-left: var(--space-5);
}

.learning-steps li {
  padding-left: var(--space-1);
  line-height: 1.55;
}

@media (prefers-reduced-motion: reduce) {
  .research-learning__fill {
    transition: none;
  }
}

@media (max-width: 620px) {
  .sound-ladder {
    grid-template-columns: 1fr;
  }
}