/* ============================================================
   student-learn.css
   ------------------------------------------------------------
   Student "学習" hub:
     .learn-panel / .learn-bar / .learn-subtabs / .learn-sub-mount
     .learn-list / .learn-card / .learn-card__*
     .learn-overlay / .learn-dialog / .learn-dialog__*
     .learn-grade / .learn-grade__*
     .learn-empty (fallback only; NVA.ui.emptyState preferred)
   ============================================================ */

.learn-panel {
  display: grid;
  gap: var(--space-4, 1rem);
  padding: var(--space-4, 1rem);
  max-width: 960px;
  margin: 0 auto;
}

.learn-panel__head { display: grid; gap: 0.25rem; }
.learn-panel__title {
  margin: 0;
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--color-text, #111827);
}
.learn-panel__sub {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--color-text-muted, #6b7280);
}

/* ── Toolbar ─────────────────────────────── */
.learn-bar {
  display: flex;
  gap: 0.75rem;
  align-items: end;
  flex-wrap: wrap;
}
.learn-bar__field {
  display: grid;
  gap: 0.25rem;
  min-width: min(240px, 100%);
}
.learn-bar__label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-text-muted, #6b7280);
}
.learn-bar__select {
  height: 2.25rem;
  padding: 0 0.625rem;
  border: 1px solid var(--color-border, #e5e7eb);
  border-radius: var(--radius-sm, 6px);
  background: var(--color-surface, #fff);
  font-size: 0.875rem;
}

/* ── Sub-tabs ────────────────────────────── */
.learn-subtabs {
  display: inline-flex;
  gap: 0.25rem;
  padding: 0.25rem;
  background: var(--color-surface-alt, #fafbfc);
  border: 1px solid var(--color-border, #e5e7eb);
  border-radius: var(--radius-md, 10px);
  width: fit-content;
}
.learn-subtabs__btn {
  appearance: none;
  border: 0;
  background: transparent;
  padding: 0.45rem 1rem;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text-muted, #6b7280);
  border-radius: var(--radius-sm, 6px);
  cursor: pointer;
}
.learn-subtabs__btn[aria-selected="true"] {
  background: var(--color-surface, #fff);
  color: var(--color-text, #111827);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
}

.learn-sub-mount {
  display: grid;
  gap: var(--space-3, 0.75rem);
}

/* ── Assignment cards ────────────────────── */
.learn-list {
  display: grid;
  gap: var(--space-3, 0.75rem);
}
.learn-card {
  display: grid;
  gap: 0.5rem;
  padding: var(--space-4, 1rem);
  border: 1px solid var(--color-border, #e5e7eb);
  border-radius: var(--radius-md, 10px);
  background: var(--color-surface, #fff);
  transition: box-shadow 0.18s ease, transform 0.18s ease;
}
.learn-card:hover {
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.06);
  transform: translateY(-1px);
}
.learn-card[data-status="graded"] {
  border-color: color-mix(in oklab, var(--color-success, #16a34a) 45%, #fff);
  background: color-mix(in oklab, var(--color-success, #16a34a) 4%, #fff);
}
.learn-card[data-status="submitted"] {
  border-color: color-mix(in oklab, var(--color-primary, #2563eb) 45%, #fff);
}
.learn-card[data-status="draft"] {
  border-style: dashed;
}

.learn-card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  flex-wrap: wrap;
}
.learn-card__title {
  margin: 0;
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text, #111827);
  flex: 1 1 auto;
}
.learn-card__badge {
  display: inline-block;
  padding: 0.15rem 0.55rem;
  font-size: 0.6875rem;
  font-weight: 700;
  border-radius: 999px;
  border: 1px solid var(--color-border, #e5e7eb);
  background: var(--color-surface-alt, #fafbfc);
  color: var(--color-text-muted, #6b7280);
}
.learn-card__badge--submitted {
  background: color-mix(in oklab, var(--color-primary, #2563eb) 12%, #fff);
  border-color: color-mix(in oklab, var(--color-primary, #2563eb) 45%, #fff);
  color: var(--color-primary, #2563eb);
}
.learn-card__badge--graded {
  background: color-mix(in oklab, var(--color-success, #16a34a) 14%, #fff);
  border-color: color-mix(in oklab, var(--color-success, #16a34a) 45%, #fff);
  color: var(--color-success, #16a34a);
}
.learn-card__badge--draft {
  background: color-mix(in oklab, var(--color-warning, #d97706) 12%, #fff);
  border-color: color-mix(in oklab, var(--color-warning, #d97706) 45%, #fff);
  color: var(--color-warning, #d97706);
}
.learn-card__desc {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--color-text, #111827);
  line-height: 1.55;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.learn-card__info {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  font-size: 0.75rem;
  color: var(--color-text-muted, #6b7280);
}
.learn-card__late {
  color: var(--color-danger, #dc2626);
  font-weight: 700;
}
.learn-card__actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.35rem;
}

/* ── Dialog ──────────────────────────────── */
.learn-overlay {
  position: fixed;
  inset: 0;
  background: rgba(17, 24, 39, 0.55);
  display: grid;
  place-items: center;
  padding: 1rem;
  z-index: 55;
  overflow: auto;
}
.learn-dialog {
  width: min(720px, 100%);
  max-height: min(90vh, 820px);
  background: var(--color-surface, #fff);
  border-radius: var(--radius-lg, 14px);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.25);
  display: grid;
  grid-template-rows: auto 1fr auto;
  overflow: hidden;
}
.learn-dialog__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--color-border, #e5e7eb);
}
.learn-dialog__title {
  margin: 0;
  font-size: 1rem;
  font-weight: 800;
  color: var(--color-text, #111827);
}
.learn-dialog__close {
  appearance: none;
  border: 0;
  background: transparent;
  font-size: 1.25rem;
  padding: 0.25rem 0.55rem;
  border-radius: var(--radius-sm, 6px);
  cursor: pointer;
  color: var(--color-text-muted, #6b7280);
}
.learn-dialog__close:hover {
  background: var(--color-surface-alt, #fafbfc);
  color: var(--color-text, #111827);
}
.learn-dialog__body {
  padding: var(--space-4, 1rem);
  overflow: auto;
  display: grid;
  gap: var(--space-3, 0.75rem);
}
.learn-dialog__section { display: grid; gap: 0.5rem; }
.learn-dialog__sec-title {
  margin: 0;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-text-muted, #6b7280);
}
.learn-dialog__desc {
  margin: 0;
  font-size: 0.875rem;
  color: var(--color-text, #111827);
  line-height: 1.6;
  white-space: pre-wrap;
}
.learn-dialog__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  font-size: 0.75rem;
  color: var(--color-text-muted, #6b7280);
}
.learn-dialog__rubric {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.25rem;
}
.learn-dialog__rubric-item {
  display: flex;
  justify-content: space-between;
  gap: 0.5rem;
  padding: 0.35rem 0.55rem;
  border: 1px solid var(--color-border, #e5e7eb);
  border-radius: var(--radius-sm, 6px);
  background: var(--color-surface-alt, #fafbfc);
  font-size: 0.8125rem;
}
.learn-dialog__rubric-label { font-weight: 600; color: var(--color-text, #111827); }
.learn-dialog__rubric-meta { font-size: 0.75rem; color: var(--color-text-muted, #6b7280); }

.learn-dialog__textarea {
  min-height: 8rem;
  resize: vertical;
  font-family: inherit;
  line-height: 1.55;
}
.learn-dialog__foot {
  display: flex;
  justify-content: flex-end;
  gap: 0.5rem;
  padding: 0.75rem 1rem;
  border-top: 1px solid var(--color-border, #e5e7eb);
  background: var(--color-surface-alt, #fafbfc);
}

/* ── Grade block ─────────────────────────── */
.learn-grade {
  padding: 0.75rem 0.85rem;
  border: 1px solid color-mix(in oklab, var(--color-success, #16a34a) 40%, #fff);
  border-radius: var(--radius-md, 10px);
  background: color-mix(in oklab, var(--color-success, #16a34a) 6%, #fff);
}
.learn-grade__headline {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
}
.learn-grade__score {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--color-success, #16a34a);
}
.learn-grade__pct {
  font-size: 0.9rem;
  font-weight: 700;
  color: color-mix(in oklab, var(--color-success, #16a34a) 70%, #000);
}
.learn-grade__rubric {
  list-style: none;
  padding: 0;
  margin: 0 0 0.5rem;
  display: grid;
  gap: 0.25rem;
}
.learn-grade__rubric-row {
  display: flex;
  justify-content: space-between;
  padding: 0.3rem 0.5rem;
  background: var(--color-surface, #fff);
  border-radius: var(--radius-sm, 6px);
  font-size: 0.8125rem;
}
.learn-grade__rubric-label { color: var(--color-text, #111827); }
.learn-grade__rubric-score {
  font-weight: 700;
  color: var(--color-success, #16a34a);
}
.learn-grade__fb {
  background: var(--color-surface, #fff);
  border-radius: var(--radius-sm, 6px);
  padding: 0.5rem 0.65rem;
  margin-top: 0.35rem;
}
.learn-grade__fb-title {
  margin: 0 0 0.15rem;
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--color-text-muted, #6b7280);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.learn-grade__fb-text {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--color-text, #111827);
  line-height: 1.55;
  white-space: pre-wrap;
}
.learn-grade__when {
  margin: 0.35rem 0 0;
  font-size: 0.7rem;
  color: var(--color-text-muted, #6b7280);
  text-align: right;
}

/* ── Fallback empty (only when NVA.ui.emptyState missing) ── */
.learn-empty {
  display: grid;
  justify-items: center;
  padding: 2rem 1rem;
  gap: 0.35rem;
  border: 1px dashed var(--color-border, #e5e7eb);
  border-radius: var(--radius-md, 10px);
  background: var(--color-surface-alt, #fafbfc);
  text-align: center;
}
.learn-empty__icon { font-size: 1.8rem; }
.learn-empty__title { margin: 0; font-weight: 700; color: var(--color-text, #111827); }
.learn-empty__hint { margin: 0; font-size: 0.8125rem; color: var(--color-text-muted, #6b7280); }

/* ── Narrow screens ──────────────────────── */
@media (max-width: 560px) {
  .learn-bar, .learn-subtabs { width: 100%; }
  .learn-bar__field { width: 100%; }
  .learn-dialog__meta { flex-direction: column; gap: 0.25rem; }
}