/* =====================================================================
   Zahlen-Memory — style.css
   Children's math memory card game for tablets
   ===================================================================== */

/* ---------------------------------------------------------------------
   CSS Custom Properties
   --------------------------------------------------------------------- */
:root {
  /* Color palette */
  --color-bg:           #F0F4F8;
  --color-card-back:    #4A90D9;   /* face-down blue */
  --color-card-front:   #FFFFFF;   /* revealed white */
  --color-solved:       #27AE60;   /* matched green */
  --color-wrong:        #F39C12;   /* wrong feedback orange */
  --color-target:       #2C3E50;   /* dark blue */
  --color-header-bg:    #4A90D9;
  --color-header-text:  #FFFFFF;
  --color-btn-primary:  #4A90D9;
  --color-btn-hover:    #357ABD;
  --color-stat-correct: #27AE60;
  --color-stat-wrong:   #F39C12;

  /* Typography */
  --font-base:          1rem;
  --font-card:          2rem;       /* 32px */
  --font-target:        2.5rem;     /* 40px */
  --font-h1:            1.5rem;
  --font-label:         1.1rem;

  /* Grid */
  --grid-cols:          4;          /* overridden by JS */
  --grid-rows:          4;          /* overridden by JS */
  --card-gap:           0.4rem;

  /* Misc */
  --border-radius:      0.75rem;
  --transition-flip:    0.45s;
  --shadow-card:        0 2px 8px rgba(0, 0, 0, 0.18);
  --shadow-board:       0 4px 20px rgba(0, 0, 0, 0.10);

  /* Layout — header height for calc */
  --header-h:           48px;
}

/* ---------------------------------------------------------------------
   Reset / Base
   --------------------------------------------------------------------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
  -webkit-user-drag: none;
}

html, body {
  height: 100%;
  overflow: hidden;          /* no scrolling — everything fits viewport */
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  touch-action: manipulation;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background-color: var(--color-bg);
  background-image: url('../images/background-grass.png');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  color: var(--color-target);
  display: flex;
  flex-direction: column;
}

button {
  cursor: pointer;
  border: none;
  font-family: inherit;
  font-size: var(--font-label);
  border-radius: var(--border-radius);
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
}

select,
label {
  font-family: inherit;
  font-size: var(--font-label);
}

/* Hidden utility — used by JS with the `hidden` attribute */
[hidden] {
  display: none !important;
}

/* ---------------------------------------------------------------------
   Header — compact, fixed height
   --------------------------------------------------------------------- */
header {
  width: 100%;
  height: var(--header-h);
  min-height: var(--header-h);
  background-color: var(--color-header-bg);
  color: var(--color-header-text);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1rem;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.18);
  z-index: 10;
}

header h1 {
  font-size: var(--font-h1);
  font-weight: 700;
  letter-spacing: 0.02em;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  min-width: 0;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* ---------------------------------------------------------------------
   Buttons — primary, restart, settings
   --------------------------------------------------------------------- */
.btn-primary {
  background-color: var(--color-btn-primary);
  color: #fff;
  padding: 0.6rem 1.4rem;
  font-weight: 600;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-card);
  transition: background-color 0.18s, transform 0.1s;
  min-height: 44px;
  min-width: 100px;
}

.btn-primary:active {
  background-color: var(--color-btn-hover);
  transform: scale(0.96);
}

.btn-primary:disabled {
  opacity: 0.45;
  cursor: not-allowed;
  transform: none;
}

.btn-restart {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: rgba(255, 255, 255, 0.22);
  color: #fff;
  padding: 0.4rem 0.9rem;
  font-size: 0.9rem;
  font-weight: 600;
  border-radius: var(--border-radius);
  border: 2px solid rgba(255, 255, 255, 0.55);
  transition: background-color 0.18s;
  min-height: 44px;
}

.btn-restart:active {
  background-color: rgba(255, 255, 255, 0.38);
}

.btn-settings {
  background: rgba(255, 255, 255, 0.22);
  color: #fff;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  border: 2px solid rgba(255, 255, 255, 0.55);
  padding: 0;
  transition: background-color 0.18s;
}

.btn-settings:active {
  background-color: rgba(255, 255, 255, 0.38);
}

.btn-teacher-show {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  min-width: 48px;
  padding: 0 0.45rem;
  background-color: rgba(255, 255, 255, 0.26);
  color: #fff;
  border: 2px solid rgba(255, 255, 255, 0.58);
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 800;
  line-height: 1;
}

.btn-teacher-show:active:not(:disabled) {
  background-color: rgba(255, 255, 255, 0.42);
}

.btn-teacher-show:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

/* ---------------------------------------------------------------------
   Settings Modal
   --------------------------------------------------------------------- */
.settings-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  animation: fadeIn 0.2s ease;
}

.settings-modal {
  background: #fff;
  border-radius: var(--border-radius);
  box-shadow: 0 8px 40px rgba(0, 0, 0, 0.25);
  padding: 1.5rem;
  width: 90%;
  max-width: 400px;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.settings-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.settings-header h2 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--color-target);
}

.btn-settings-close {
  background: none;
  color: var(--color-target);
  font-size: 1.8rem;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  line-height: 1;
  padding: 0;
}

.btn-settings-close:active {
  background: var(--color-bg);
}

.config-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.config-row label {
  font-weight: 600;
  color: var(--color-target);
  white-space: nowrap;
}

.config-row select {
  flex: 1;
  max-width: 180px;
  padding: 0.5rem 0.75rem;
  border: 2px solid #CBD5E0;
  border-radius: 0.5rem;
  background: #F7FAFC;
  color: var(--color-target);
  appearance: auto;
  font-size: var(--font-label);
  min-height: 44px;
}

.config-buttons {
  display: flex;
  gap: 0.75rem;
  justify-content: stretch;
}

.config-buttons .btn-primary {
  flex: 1;
}

/* ---------------------------------------------------------------------
   Game area — fills remaining viewport
   --------------------------------------------------------------------- */
.game-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.4rem;
  min-height: 0;               /* allow flex shrink */
  overflow: hidden;
}

/* ---------------------------------------------------------------------
   Target display — compact
   --------------------------------------------------------------------- */
.target-display {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background: #fff;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-board);
  padding: 0.3rem 1.5rem;
  width: 100%;
  max-width: 520px;
  flex-shrink: 0;
}

.target-label {
  font-size: var(--font-label);
  color: var(--color-target);
  font-weight: 500;
}

.target-number {
  font-size: var(--font-target);
  font-weight: 800;
  color: var(--color-card-back);
  line-height: 1;
  min-width: 2ch;
  text-align: center;
}

/* ---------------------------------------------------------------------
   Board — CSS Grid, sized to fit viewport
   --------------------------------------------------------------------- */
.board {
  display: grid;
  grid-template-columns: repeat(var(--grid-cols), 1fr);
  grid-template-rows: repeat(var(--grid-rows), 1fr);
  gap: var(--card-gap);
  padding: var(--card-gap);
  width: 100%;
  max-width: min(92vw, calc((90vh - var(--header-h) - 100px) * var(--grid-cols) / var(--grid-rows)));
  max-height: calc(90vh - var(--header-h) - 100px);
  aspect-ratio: var(--grid-cols) / var(--grid-rows);
  background: rgba(255, 255, 255, 0.55);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-board);
  flex-shrink: 1;
  min-height: 0;
}

/* Empty board — no visual chrome */
.board:empty {
  background: transparent;
  box-shadow: none;
  padding: 0;
  aspect-ratio: auto;
}

/* ---------------------------------------------------------------------
   Card — 3D flip container, sized by grid
   --------------------------------------------------------------------- */
.card {
  width: 100%;
  aspect-ratio: 1;
  perspective: 600px;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

/* Inner wrapper — the element that actually flips */
.card-inner {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform var(--transition-flip) cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: var(--border-radius);
}

/* Card faces — shared base */
.card-front,
.card-back {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--border-radius);
  font-size: var(--font-card);
  font-weight: 800;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  box-shadow: var(--shadow-card);
  line-height: 1;
}

/* Face-down side (blue "?") — shown by default */
.card-front {
  background-color: var(--color-card-back);
  color: #fff;
}

/* Face-up side (white with number) — hidden by default */
.card-back {
  background-color: var(--color-card-front);
  color: var(--color-target);
  transform: rotateY(180deg);
  border: 2px solid #CBD5E0;
}

/* ---------------------------------------------------------------------
   Card states
   --------------------------------------------------------------------- */

/* revealed: card flipped to show number */
.card.revealed .card-inner {
  transform: rotateY(180deg);
}

.board.teacher-preview .card:not(.solved) .card-inner {
  transform: rotateY(180deg);
}

.board.teacher-preview .card:not(.solved) .card-back {
  border-color: var(--color-card-back);
  box-shadow: 0 0 0 3px rgba(74, 144, 217, 0.22), var(--shadow-card);
}

/* solved: flipped + green tint, no more interaction */
.card.solved {
  cursor: default;
  pointer-events: none;
}

.board.finished-board .card.solved {
  cursor: pointer;
  pointer-events: auto;
}

.card.solved .card-inner {
  transform: rotateY(180deg);
}

.card.solved .card-back {
  background-color: #E8F8F0;
  border-color: var(--color-solved);
  color: var(--color-solved);
}

.card.solved .card-front {
  background-color: var(--color-solved);
}

/* wrong: orange flash feedback */
.card.wrong .card-inner {
  transform: rotateY(180deg);
}

.card.wrong .card-back {
  animation: wrongFlashBg 0.55s ease forwards;
}

@keyframes wrongFlashBg {
  0%   { background-color: var(--color-card-front); border-color: var(--color-wrong); }
  25%  { background-color: #FDEBD0; border-color: var(--color-wrong); }
  75%  { background-color: #FDEBD0; border-color: var(--color-wrong); }
  100% { background-color: var(--color-card-front); border-color: #CBD5E0; }
}

/* Disabled during evaluation — no pointer events on whole board */
.board.locked .card:not(.solved) {
  pointer-events: none;
}

/* ---------------------------------------------------------------------
   Stats bar — compact
   --------------------------------------------------------------------- */
.stats {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.2rem;
  background: #fff;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-board);
  padding: 0.3rem 1.2rem;
  width: 100%;
  max-width: 520px;
  font-size: 0.95rem;
  font-weight: 500;
  flex-shrink: 0;
}

.stats strong {
  font-size: 1.1em;
  font-weight: 700;
}

.stat-correct {
  color: var(--color-stat-correct);
}

.stat-wrong {
  color: var(--color-stat-wrong);
}

/* ---------------------------------------------------------------------
   Summary screen
   --------------------------------------------------------------------- */
.summary {
  position: fixed;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1.25rem;
  background: rgba(240, 244, 248, 0.95);
  z-index: 50;
  animation: fadeIn 0.35s ease;
  padding: 2rem;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

.summary h2 {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--color-solved);
}

.summary-stats {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  font-size: 1.15rem;
  text-align: center;
}

.summary-stats strong {
  font-weight: 700;
}

.summary-stats .stat-correct {
  color: var(--color-stat-correct);
}

.summary-stats .stat-wrong {
  color: var(--color-stat-wrong);
}

/* ---------------------------------------------------------------------
   Confetti — final successful match
   --------------------------------------------------------------------- */
.confetti-layer {
  position: fixed;
  inset: 0;
  z-index: 80;
  pointer-events: none;
  overflow: hidden;
}

.confetti-piece {
  position: absolute;
  width: var(--piece-w, 0.55rem);
  height: var(--piece-h, 0.82rem);
  border-radius: 0.18rem;
  background: var(--color);
  transform: translate(-50%, -50%);
  animation: confettiBurst 1.45s ease-out forwards;
  will-change: transform, opacity;
}

@keyframes confettiBurst {
  0% {
    opacity: 1;
    transform: translate(-50%, -50%) rotate(0deg) scale(1);
  }
  74% {
    opacity: 1;
  }
  100% {
    opacity: 0;
    transform: translate(calc(-50% + var(--dx)), calc(-50% + var(--dy))) rotate(var(--spin)) scale(0.75);
  }
}

/* ---------------------------------------------------------------------
   Welcome state — when no game is active, show centered prompt
   --------------------------------------------------------------------- */
.game-area:not(:has(.card)) {
  justify-content: center;
}

.game-area:not(:has(.card))::after {
  content: 'Tippe auf das Zahnrad oben rechts, um ein Spiel zu starten.';
  font-size: 1.1rem;
  color: #8899A6;
  text-align: center;
  padding: 2rem;
  max-width: 300px;
}

/* ---------------------------------------------------------------------
   Responsive — scale card font for smaller cards
   --------------------------------------------------------------------- */

/* Scale font for grids with 5 columns */
.board[style*="--grid-cols: 5"] .card-front,
.board[style*="--grid-cols: 5"] .card-back,
.board[style*="--grid-cols:5"] .card-front,
.board[style*="--grid-cols:5"] .card-back {
  font-size: 1.5rem;
}

/* Scale font for grids with 6+ columns */
.board[style*="--grid-cols: 6"] .card-front,
.board[style*="--grid-cols: 6"] .card-back,
.board[style*="--grid-cols:6"] .card-front,
.board[style*="--grid-cols:6"] .card-back,
.board[style*="--grid-cols: 7"] .card-front,
.board[style*="--grid-cols: 7"] .card-back,
.board[style*="--grid-cols:7"] .card-front,
.board[style*="--grid-cols:7"] .card-back {
  font-size: 1.3rem;
}

/* Tablet portrait: up to 820px */
@media (max-width: 820px) {
  :root {
    --font-h1:     1.3rem;
    --font-label:  1rem;
    --font-card:   1.75rem;
    --font-target: 2.2rem;
    --card-gap:    0.35rem;
  }
}

/* Smaller tablets / large phones: up to 600px */
@media (max-width: 600px) {
  :root {
    --font-h1:     1.2rem;
    --font-label:  0.95rem;
    --font-card:   1.5rem;
    --font-target: 1.8rem;
    --card-gap:    0.25rem;
  }

  header {
    padding: 0 0.75rem;
  }
}

/* Landscape — shorter viewport, tighter layout */
@media (max-height: 600px) and (orientation: landscape) {
  :root {
    --header-h:    40px;
    --font-target: 1.5rem;
    --font-card:   1.3rem;
    --card-gap:    0.2rem;
  }

  .game-area {
    gap: 0.25rem;
    padding: 0.25rem;
  }

  .target-display {
    padding: 0.2rem 1rem;
  }

  .stats {
    padding: 0.2rem 1rem;
  }
}

/* Large tablets (iPad Pro) */
@media (min-width: 1024px) {
  :root {
    --font-card:   2.2rem;
    --font-target: 3rem;
    --card-gap:    0.5rem;
  }
}