/* Chem Balancing: layout only. Tokens and base elements come from ../shared/base.css. */
.tabs { margin-bottom: 28px; }

.section { display: none; }
.section.active { display: block; }

.prompt { color: var(--ink-2); font-weight: 500; margin-bottom: 14px; }
.prompt strong { color: var(--ink); }

/* the equation or species is the hero */
.question-text {
  font-size: clamp(1.9rem, 1.2rem + 3.2vw, 2.9rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.25;
  background: var(--chem);
  border: var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  margin-bottom: 22px;
  overflow-wrap: anywhere;
}
.question-text sub, .question-text sup { font-size: 0.55em; line-height: 0; }

.input-row { display: flex; gap: 8px; margin-bottom: 8px; }
.input-row input { flex: 1; min-width: 0; }

.hint { font-size: 0.9rem; color: var(--ink-2); margin-bottom: 18px; }

.feedback { margin-bottom: 14px; }
.feedback:empty { display: none; }

.next-btn { display: none; }
.next-btn.visible { display: inline-block; }

.note {
  margin-top: 36px;
  padding-top: 16px;
  border-top: 2px solid var(--line-soft);
  font-size: 0.9rem;
  color: var(--ink-2);
}

.footer { margin-top: 48px; font-size: 0.8rem; color: var(--ink-3); text-align: center; }
.footer a { text-decoration: none; }

.visually-hidden {
  position: absolute; width: 1px; height: 1px; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap;
}

@media (max-width: 420px) {
  .input-row { flex-direction: column; }
  .question-text { padding: 22px 18px; }
}