src/components/Charts.css

.charts {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.chart-container h2 {
  margin: 0 0 1rem;
  font-size: 1.2rem;
}

.chart-span-2 {
  grid-column: 1 / -1;
}

.charts > .empty-message {
  grid-column: 1 / -1;
  text-align: center;
  padding: 2rem;
  color: var(--color-text-muted);
}

.empty-chart-message {
  margin: 0;
  color: var(--color-text-muted);
}

.grade-tooltip {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 0.45rem 0.6rem;
  font-size: 0.8rem;
  line-height: 1.4;
}

.grade-tooltip p {
  margin: 0;
}

.tooltip-date {
  color: var(--color-text);
  margin-bottom: 0.2rem !important;
}

@media (max-width: 768px) {
  .charts {
    grid-template-columns: 1fr;
  }

  .chart-span-2 {
    grid-column: auto;
  }
}