/* ============================================================
   Revision Mode — Flashcard UI
   ============================================================ */

.revision-mode {
  display: flex;
  flex-direction: column;
  min-height: calc(100vh - var(--navbar-height));
  max-width: 880px;
  margin: 0 auto;
  padding: 0 24px 24px;
}

/* ── Header ── */
.revision-header {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 16px;
  padding: 20px 0 16px;
}

.revision-header__back {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  color: var(--color-text-secondary);
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition:
    background-color var(--duration-fast) var(--ease-out),
    color var(--duration-fast) var(--ease-out);
}

.revision-header__back:hover {
  color: var(--color-text-primary);
  background: var(--color-bg-hover);
}

.revision-header__center {
  text-align: center;
  min-width: 0;
}

.revision-header__breadcrumb {
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-medium);
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 10px;
}

.revision-header__count {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-secondary);
  font-variant-numeric: tabular-nums;
}

/* ── Pipeline: Keywords ↓ KB ↓ Notes ── */
.revision-pipeline {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 6px 4px;
}

.revision-pipeline__step {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 12px;
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-tertiary);
  background: var(--color-bg-subtle);
  border: 1px solid transparent;
  border-radius: var(--radius-full);
  transition:
    color var(--duration-fast) var(--ease-out),
    background-color var(--duration-fast) var(--ease-out),
    border-color var(--duration-fast) var(--ease-out);
}

.revision-pipeline__step.is-active {
  color: var(--color-accent);
  background: var(--color-accent-soft);
  border-color: color-mix(in srgb, var(--color-accent) 25%, var(--color-border));
}

.revision-pipeline__step.is-empty {
  opacity: 0.45;
}

.revision-pipeline__count {
  font-variant-numeric: tabular-nums;
  opacity: 0.7;
}

.revision-pipeline__arrow {
  font-size: var(--font-size-xs);
  color: var(--color-text-tertiary);
  line-height: 1;
  user-select: none;
}

/* ── Progress bar ── */
.revision-progress {
  height: 3px;
  background: var(--color-bg-subtle);
  border-radius: var(--radius-full);
  overflow: hidden;
  margin-bottom: 8px;
}

.revision-progress__bar {
  display: block;
  height: 100%;
  background: var(--color-accent);
  border-radius: var(--radius-full);
  transition: width var(--duration-normal) var(--ease-out);
}

/* ── Stage ── */
.revision-stage {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px 0;
  min-height: 320px;
}

/* ── Flashcard ── */
.revision-flashcard {
  width: 100%;
  max-width: 560px;
  min-height: 300px;
  perspective: 1200px;
  cursor: pointer;
  user-select: none;
}

.revision-flashcard__inner {
  position: relative;
  width: 100%;
  min-height: 300px;
  transform-style: preserve-3d;
  transition: transform 0.55s var(--ease-out);
}

.revision-flashcard.is-revealed .revision-flashcard__inner {
  transform: rotateY(180deg);
}

.revision-flashcard__face {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 36px 32px;
  text-align: center;
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.revision-flashcard__face--back {
  transform: rotateY(180deg);
}

.revision-flashcard__type {
  position: absolute;
  top: 18px;
  left: 50%;
  transform: translateX(-50%);
  padding: 4px 10px;
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-medium);
  color: var(--color-accent);
  background: var(--color-accent-soft);
  border-radius: var(--radius-full);
}

.revision-flashcard__meta {
  position: absolute;
  top: 18px;
  right: 18px;
  font-size: var(--font-size-xs);
  color: var(--color-text-tertiary);
  max-width: 40%;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.revision-flashcard__prompt {
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-tight);
  letter-spacing: var(--letter-spacing-tight);
  color: var(--color-text-primary);
  max-width: 100%;
  word-break: break-word;
}

.revision-flashcard__answer {
  font-size: var(--font-size-base);
  line-height: var(--line-height-relaxed);
  color: var(--color-text-secondary);
  text-align: left;
  width: 100%;
  max-height: 220px;
  overflow-y: auto;
  word-break: break-word;
}

.revision-flashcard__hint {
  position: absolute;
  bottom: 20px;
  font-size: var(--font-size-xs);
  color: var(--color-text-tertiary);
}

.revision-flashcard.is-revealed .revision-flashcard__hint {
  display: none;
}

/* ── Empty state ── */
.revision-empty {
  text-align: center;
  padding: 48px 24px;
}

.revision-empty__icon {
  color: var(--color-text-tertiary);
  margin-bottom: 16px;
}

.revision-empty__title {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-primary);
  margin-bottom: 8px;
}

.revision-empty__text {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  max-width: 320px;
  margin: 0 auto;
}

/* ── Footer ── */
.revision-footer {
  padding-top: 8px;
  border-top: 1px solid var(--color-border);
}

.revision-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  margin-bottom: 16px;
}

.revision-action {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 44px;
  padding: 0 18px;
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-secondary);
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition:
    background-color var(--duration-fast) var(--ease-out),
    color var(--duration-fast) var(--ease-out),
    border-color var(--duration-fast) var(--ease-out);
}

.revision-action:hover:not(:disabled) {
  color: var(--color-text-primary);
  background: var(--color-bg-hover);
  border-color: var(--color-border-strong);
}

.revision-action:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.revision-action--primary {
  color: var(--color-text-inverse);
  background: var(--color-accent);
  border-color: var(--color-accent);
}

.revision-action--primary:hover:not(:disabled) {
  color: var(--color-text-inverse);
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
}

.revision-tools {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  margin-bottom: 18px;
}

.revision-tool {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  height: 36px;
  padding: 0 14px;
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-secondary);
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  transition:
    color var(--duration-fast) var(--ease-out),
    background-color var(--duration-fast) var(--ease-out),
    border-color var(--duration-fast) var(--ease-out);
}

.revision-tool:hover:not(:disabled) {
  color: var(--color-text-primary);
  background: var(--color-bg-subtle);
}

.revision-tool.is-active {
  color: var(--color-accent);
  background: var(--color-accent-soft);
  border-color: color-mix(in srgb, var(--color-accent) 35%, var(--color-border));
}

.revision-tool:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

/* ── Keyboard hints ── */
.revision-shortcuts {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 8px 16px;
}

.revision-shortcuts__item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: var(--font-size-xs);
  color: var(--color-text-tertiary);
}

.revision-shortcuts kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 22px;
  height: 22px;
  padding: 0 6px;
  font-family: inherit;
  font-size: 0.6875rem;
  font-weight: var(--font-weight-medium);
  color: var(--color-text-secondary);
  background: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
  border-radius: 5px;
  box-shadow: 0 1px 0 var(--color-border);
}

/* ── Responsive ── */
@media (max-width: 640px) {
  .revision-mode {
    padding: 0 16px 20px;
  }

  .revision-header {
    grid-template-columns: auto 1fr;
    grid-template-rows: auto auto;
  }

  .revision-header__progress {
    grid-column: 2;
    justify-self: end;
  }

  .revision-pipeline__label {
    font-size: 0.6875rem;
  }

  .revision-flashcard__prompt {
    font-size: var(--font-size-lg);
  }

  .revision-flashcard__face {
    padding: 32px 20px;
  }

  .revision-action span {
    display: none;
  }

  .revision-action {
    width: 44px;
    padding: 0;
    justify-content: center;
  }

  .revision-shortcuts {
    gap: 6px 10px;
  }
}