/* =============================================================================
   BUAMS AI new-ui — EMPTY / LOADING / ERROR STATES
   Spec: /frontend_design.md §F.4

   Every async region must specify all of loading / empty / error before it
   ships. These are designed states, not afterthoughts (Design Principle 2).
   ============================================================================= */

/* ── Empty state ──────────────────────────────────────────────────────────── */
.bui-empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: var(--bui-space-12) var(--bui-space-6);
}

.bui-empty-icon {
  display: grid;
  place-items: center;
  width: 56px;
  height: 56px;
  margin-bottom: var(--bui-space-4);
  background: var(--bui-primary-50);
  border-radius: var(--bui-radius-pill);
  color: var(--bui-primary-700);
  font-size: 1.5rem;
}

.bui-empty-title {
  margin-bottom: var(--bui-space-2);
  font-size: var(--bui-text-h3);
  font-weight: var(--bui-fw-bold);
  color: var(--bui-ink-900);
}

.bui-empty-sub {
  max-width: 44ch;
  margin-bottom: var(--bui-space-5);
  font-size: var(--bui-text-sm);
  color: var(--bui-ink-500);
}

/* ── Inline loading ───────────────────────────────────────────────────────── */
.bui-loading {
  display: inline-flex;
  align-items: center;
  gap: var(--bui-space-2);
  font-size: var(--bui-text-sm);
  color: var(--bui-ink-500);
}

.bui-spinner {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
  border: 2px solid var(--bui-line-strong);
  border-top-color: var(--bui-primary-700);
  border-radius: 50%;
  animation: bui-spin .6s linear infinite;
}

.bui-spinner-lg {
  width: 28px;
  height: 28px;
  border-width: 3px;
}

/* ── Skeleton ─────────────────────────────────────────────────────────────── */
.bui-skeleton {
  background: linear-gradient(
    90deg,
    var(--bui-disabled-bg) 25%,
    var(--bui-surface-2) 50%,
    var(--bui-disabled-bg) 75%
  );
  background-size: 200% 100%;
  border-radius: var(--bui-radius-sm);
  animation: bui-shimmer 1.4s ease-in-out infinite;
}

@keyframes bui-shimmer {
  0%   { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

.bui-skeleton-text {
  height: 12px;
  margin-bottom: var(--bui-space-2);
}

.bui-skeleton-text:last-child {
  width: 70%;
  margin-bottom: 0;
}

/* ── Full-region error ────────────────────────────────────────────────────── */
.bui-state-error {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: var(--bui-space-10) var(--bui-space-6);
}

.bui-state-error-icon {
  display: grid;
  place-items: center;
  width: 56px;
  height: 56px;
  margin-bottom: var(--bui-space-4);
  background: var(--bui-danger-bg);
  border-radius: var(--bui-radius-pill);
  color: var(--bui-danger);
  font-size: 1.5rem;
}

/* ── Screen-reader live region ────────────────────────────────────────────
   Async status announced without a visible element. Paired with
   aria-live="polite" in the markup. */
.bui-live {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 575.98px) {
  .bui-empty,
  .bui-state-error {
    padding: var(--bui-space-8) var(--bui-space-4);
  }
}