/* ================================================
   STUDY PAGE - Modern CSS with Grid, Container Queries
   Baseline 2024 features: container queries, :has(),
   logical properties, color-mix(), aspect-ratio
   ================================================ */

/* ================================================
   PAGE LAYOUT - CSS Grid with named areas
   ================================================ */
.study-page {
  display: grid;
  grid-template-rows: auto auto 1fr auto;
  grid-template-areas:
    "header"
    "progress"
    "content"
    "footer";
  min-block-size: 100vh;
  min-block-size: 100dvh;
  background: var(--background);
  view-transition-name: page-content;
}

/* ================================================
   PROGRESS BAR - Shared component (matches game)
   ================================================ */
.study-page .progress-bar {
  grid-area: progress;
  block-size: 6px;
  margin-inline: var(--space-xs);
  background: color-mix(in oklch, var(--border) 60%, transparent);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.study-page .progress-fill {
  block-size: 100%;
  inline-size: 0%;
  background: linear-gradient(
    90deg,
    var(--primary),
    color-mix(in oklch, var(--correct) 80%, var(--primary))
  );
  border-radius: var(--radius-full);
  transition: inline-size var(--duration-slow) var(--ease-out);
}

/* ================================================
   STUDY CONTENT - Centered with container queries
   ================================================ */
.study-content {
  grid-area: content;
  display: grid;
  place-items: center;
  align-content: center;
  padding: var(--space-md);
  gap: var(--space-md);
  max-inline-size: var(--container-sm);
  margin-inline: auto;
  inline-size: 100%;
  container-type: inline-size;
  container-name: study-content;
}

/* ================================================
   STATS BAR - Known/Learning counters
   ================================================ */
.stats-bar {
  display: flex;
  gap: var(--space-sm);
  justify-content: center;
}

.badge {
  display: inline-grid;
  grid-auto-flow: column;
  place-items: center;
  gap: 4px;
  padding: var(--space-2xs) var(--space-xs);
  border-radius: var(--radius-full);
  font-weight: var(--font-weight-semibold);
  font-size: var(--font-size-xs);
  font-variant-numeric: tabular-nums;
}

.badge-success {
  background: var(--correct-bg);
  color: var(--correct);
}

.badge-warning {
  background: var(--wrong-bg);
  color: var(--wrong);
}

@media (prefers-color-scheme: dark) {
  .badge-success {
    background: color-mix(in oklch, var(--correct) 20%, transparent);
  }

  .badge-warning {
    background: color-mix(in oklch, var(--wrong) 20%, transparent);
  }
}

/* ================================================
   CARDS CONTAINER - 3D perspective wrapper
   ================================================ */
.cards-container {
  position: relative;
  inline-size: 100%;
  max-inline-size: 320px;
  aspect-ratio: 3 / 4;
  perspective: 1200px;
  container-type: inline-size;
  container-name: card-stack;
}

.cards-container.hidden {
  display: none;
}

/* Container query for larger cards */
@container study-content (min-width: 400px) {
  .cards-container {
    max-inline-size: 360px;
  }
}

/* ================================================
   STUDY CARD - 3D flip card with gestures
   ================================================ */
.study-card {
  position: absolute;
  inset: 0;
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-card);
  cursor: grab;
  user-select: none;
  touch-action: pan-y;
  transform-style: preserve-3d;
  transition:
    transform var(--duration-slow) var(--ease-out),
    opacity var(--duration-slow) var(--ease-out),
    box-shadow var(--duration-normal) var(--ease-out);
}

.study-card:hover {
  box-shadow: var(--shadow-card-hover);
}

.study-card:active {
  cursor: grabbing;
}

.study-card:focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 3px;
}

/* Card stack effect using :nth-child would require JS changes */
/* Using data-position attribute instead */
.study-card[data-position="0"] {
  z-index: 3;
}

.study-card[data-position="1"] {
  z-index: 2;
  transform: scale(0.95) translateY(10px);
  opacity: 0.8;
}

.study-card[data-position="2"] {
  z-index: 1;
  transform: scale(0.9) translateY(20px);
  opacity: 0.6;
}

/* Dragging states */
.study-card.dragging {
  transition: none;
  cursor: grabbing;
}

.study-card.swiping-left {
  transform: translateX(-150%) rotate(-25deg);
  opacity: 0;
}

.study-card.swiping-right {
  transform: translateX(150%) rotate(25deg);
  opacity: 0;
}

@media (prefers-reduced-motion: reduce) {
  .study-card {
    transition: none;
  }

  .study-card.swiping-left,
  .study-card.swiping-right {
    opacity: 0;
    transform: none;
  }
}

/* ================================================
   CARD FACES - Front & Back with 3D flip
   ================================================ */
.card-face {
  position: absolute;
  inset: 0;
  padding: var(--space-md);
  display: grid;
  grid-template-rows: auto 1fr;
  gap: var(--space-sm);
  backface-visibility: hidden;
  border-radius: var(--radius-xl);
  overflow: hidden;
}

.card-back {
  transform: rotateY(180deg);
  place-content: center;
  place-items: center;
  text-align: center;
  background: var(--surface-1);
}

.study-card.flipped {
  transform: rotateY(180deg);
}

.study-card.flipped[data-position="1"] {
  transform: scale(0.95) translateY(10px) rotateY(180deg);
}

.study-card.flipped[data-position="2"] {
  transform: scale(0.9) translateY(20px) rotateY(180deg);
}

@media (prefers-reduced-motion: reduce) {
  .study-card.flipped {
    transform: none;
  }

  .study-card.flipped .card-front {
    visibility: hidden;
  }

  .study-card.flipped .card-back {
    visibility: visible;
    transform: none;
  }
}

/* ================================================
   AUXILIARY BADGE - Hebben/Zijn indicator
   ================================================ */
.study-card .aux-badge {
  position: absolute;
  inset-block-start: var(--space-sm);
  inset-inline-end: var(--space-sm);
  padding: var(--space-2xs) var(--space-xs);
  border-radius: var(--radius-full);
  font-size: 0.625rem;
  font-weight: var(--font-weight-semibold);
  text-transform: lowercase;
  letter-spacing: 0.02em;
}

.study-card .aux-badge.hebben {
  background: var(--hebben-bg);
  color: var(--hebben-text);
}

.study-card .aux-badge.zijn {
  background: var(--zijn-bg);
  color: var(--zijn-text);
}

/* ================================================
   CARD CONTENT - Verb forms display
   ================================================ */
.study-card .infinitive {
  margin-block-start: var(--space-md);
  font-size: clamp(1.25rem, 8cqi, 1.75rem);
  font-weight: var(--font-weight-bold);
  color: var(--text);
  line-height: var(--line-height-tight);
}

.study-card .forms {
  display: grid;
  gap: var(--space-sm);
  margin-block-start: var(--space-sm);
}

.study-card .form-row {
  display: grid;
  gap: var(--space-2xs);
}

.study-card .form-label {
  font-size: 0.625rem;
  font-weight: var(--font-weight-medium);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.study-card .form-value {
  font-size: clamp(0.875rem, 5cqi, 1.125rem);
  font-weight: var(--font-weight-medium);
  color: var(--text);
}

.study-card .translation {
  font-size: clamp(1.125rem, 7cqi, 1.5rem);
  font-weight: var(--font-weight-semibold);
  color: var(--text);
  text-wrap: balance;
}

/* ================================================
   SWIPE INDICATORS - Visual feedback
   ================================================ */
.swipe-indicator {
  position: absolute;
  inset-block-start: 50%;
  transform: translateY(-50%);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-md);
  font-weight: var(--font-weight-bold);
  font-size: var(--font-size-lg);
  opacity: 0;
  transition: opacity var(--duration-fast);
}

.swipe-indicator.left {
  inset-inline-start: var(--space-sm);
  background: var(--wrong-bg);
  color: var(--wrong);
}

.swipe-indicator.right {
  inset-inline-end: var(--space-sm);
  background: var(--correct-bg);
  color: var(--correct);
}

.study-card.showing-left .swipe-indicator.left,
.study-card.showing-right .swipe-indicator.right {
  opacity: 1;
}

/* ================================================
   INSTRUCTIONS - Keyboard hints
   ================================================ */
.instructions {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: start;
  padding: var(--space-md) var(--space-xs);
  gap: var(--space-md);
  inline-size: 100%;
  max-inline-size: 320px;
}

.instructions.hidden {
  display: none;
}

@container study-content (min-width: 400px) {
  .instructions {
    max-inline-size: 360px;
  }
}

.instruction {
  display: grid;
  gap: var(--space-2xs);
  text-align: center;
}

.instruction.left {
  justify-items: start;
  text-align: start;
}

.instruction.right {
  justify-items: end;
  text-align: end;
}

.instruction.center {
  justify-items: center;
}

.instruction-keys {
  display: flex;
  gap: 2px;
}

.instruction-label {
  font-size: 0.625rem;
  font-weight: var(--font-weight-medium);
  color: var(--text-muted);
}

.instruction.left .instruction-label {
  color: var(--wrong);
}

.instruction.right .instruction-label {
  color: var(--correct);
}

/* Keyboard hint styling */
.kbd {
  display: inline-grid;
  place-items: center;
  min-inline-size: 1.5em;
  padding: 0.1em 0.35em;
  font-family: var(--font-mono);
  font-size: 0.625rem;
  font-weight: var(--font-weight-medium);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  box-shadow: inset 0 -1px 0 var(--border);
  color: var(--text-secondary);
}

@media (prefers-color-scheme: dark) {
  .kbd {
    background: var(--surface-3);
  }
}

/* ================================================
   EMPTY STATE - Completion message
   ================================================ */
.empty-state {
  display: none;
  grid-template-rows: auto auto auto auto;
  place-items: center;
  text-align: center;
  gap: var(--space-md);
  padding: var(--space-lg);
}

.empty-state:not([hidden]) {
  display: grid;
}

.empty-icon {
  font-size: 3rem;
  line-height: 1;
}

.empty-state h2 {
  margin: 0;
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-bold);
  color: var(--text);
}

.empty-state p {
  margin: 0;
  font-size: var(--font-size-sm);
  color: var(--text-muted);
}

/* ================================================
   RESTART BUTTON - Matches game button style
   ================================================ */
.restart-btn {
  display: inline-grid;
  place-items: center;
  grid-auto-flow: column;
  gap: var(--space-xs);
  margin-block-start: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  min-block-size: 48px;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: var(--radius-lg);
  font: inherit;
  font-weight: var(--font-weight-semibold);
  font-size: var(--font-size-sm);
  cursor: pointer;
  transition:
    background var(--duration-fast) var(--ease-out),
    transform var(--duration-fast) var(--ease-out);
}

.restart-btn:hover {
  background: var(--primary-hover);
}

.restart-btn:active {
  transform: scale(0.98);
}

.restart-btn:focus-visible {
  outline: 2px solid var(--focus-ring);
  outline-offset: 2px;
}

/* ================================================
   DARK MODE ADJUSTMENTS
   ================================================ */
@media (prefers-color-scheme: dark) {
  .study-card {
    border-color: color-mix(in oklch, var(--border) 80%, transparent);
  }
}