/* ============================================================
   game.css — Custom styles for Emoji Memory Match
   Google Font: Nunito (imported via <link> in index.html)
   ============================================================ */

/* ─── CSS CUSTOM PROPERTIES (at least 3 required) ─── */
:root {
  --color-primary:    #0d6efd;
  --color-success:    #198754;
  --color-bg-light:   #f8f9fa;
  --color-bg-dark:    #121212;
  --color-card-back:  #6c757d;
  --color-card-front: #ffffff;
  --color-matched:    #198754;
  --color-text-dark:  #1a1a2e;
  --color-text-light: #f8f9fa;
  --spacing-sm:       0.5rem;
  --spacing-md:       1rem;
  --spacing-lg:       1.5rem;
  --card-size:        90px;
  --card-radius:      12px;
  --transition-speed: 0.4s;
  --font-family:      'Nunito', sans-serif;
}

/* ─── BASE / RESET ───────────────────────────────────── */
*, *::before, *::after {
  box-sizing: border-box;
}

body {
  font-family: var(--font-family);
  background-color: var(--color-bg-light);
  color: var(--color-text-dark);
  transition: background-color 0.3s ease, color 0.3s ease;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ─── DARK THEME ─────────────────────────────────────── */
body[data-theme="dark"] {
  background-color: var(--color-bg-dark);
  color: var(--color-text-light);
}

/* Advanced selector: adjacent sibling — dark theme cards */
body[data-theme="dark"] .card {
  background-color: #1e1e2e;
  border-color: #444;
  color: var(--color-text-light);
}

body[data-theme="dark"] .footer {
  background-color: #1e1e2e !important;
  border-top: 1px solid #333;
}

body[data-theme="dark"] .alert-info {
  background-color: #1e3a5f;
  border-color: #3a7bd5;
  color: #a8d4ff;
}

/* ─── RAINBOW EASTER EGG THEME ───────────────────────── */
/* Advanced selector: :is() pseudo-class */
body.theme-rainbow :is(.memory-card, .badge, .navbar) {
  animation: rainbowShift 2s linear infinite;
}

@keyframes rainbowShift {
  0%   { filter: hue-rotate(0deg); }
  100% { filter: hue-rotate(360deg); }
}

/* ─── NAVBAR ─────────────────────────────────────────── */
.navbar-brand {
  font-size: 1.4rem;
  font-weight: 800;
  letter-spacing: -0.5px;
}

/* Advanced selector: nth-child — alternating nav items */
.navbar-nav .nav-item:nth-child(odd) .btn {
  opacity: 0.95;
}

/* ─── MAIN / CONTENT ──────────────────────────────────── */
main.container {
  flex: 1;
}

/* ─── SETTINGS CARD ──────────────────────────────────── */
.card.shadow-sm {
  border-radius: var(--card-radius);
}

/* ─── GAME BOARD ─────────────────────────────────────── */
/* Responsive CSS Grid layout */
.game-board {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(var(--card-size), 1fr));
  gap: var(--spacing-sm);
  justify-content: center;
  padding: var(--spacing-sm);
}

/* Card column wrapper */
.card-col {
  display: flex;
  justify-content: center;
  align-items: center;
}

/* ─── MEMORY CARD ─────────────────────────────────────── */
.memory-card {
  position: relative;
  width: var(--card-size);
  height: var(--card-size);
  border: none;
  border-radius: var(--card-radius);
  background: transparent;
  cursor: pointer;
  perspective: 800px;
  /* Focus outline for keyboard accessibility */
  outline-offset: 3px;
}

/* Focus-visible outline — keyboard users only */
.memory-card:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 4px;
}

/* Card inner wrapper — flips on .is-flipped */
.memory-card .card-face {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--card-radius);
  font-size: 2.2rem;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  transition: transform var(--transition-speed) ease;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

/* Card back (visible by default — shows ?) */
.card-back {
  background-color: var(--color-card-back);
  color: white;
  transform: rotateY(0deg);
}

/* Card front (hidden by default — shows emoji) */
.card-front {
  background-color: var(--color-card-front);
  color: var(--color-text-dark);
  transform: rotateY(180deg);
}

/* Flipped state */
.memory-card.is-flipped .card-back  { transform: rotateY(-180deg); }
.memory-card.is-flipped .card-front { transform: rotateY(0deg); }

/* Matched state */
.memory-card.is-matched .card-front {
  background-color: var(--color-matched);
  color: white;
}

/* Advanced selector: attribute selector — disabled cards */
.memory-card[disabled] {
  cursor: default;
}

/* Hover effect (non-matched, non-disabled) */
.memory-card:not([disabled]):not(.is-matched):hover {
  transform: scale(1.08);
}

/* ─── BADGES / SCORE DISPLAY ──────────────────────────── */
.badge.fs-6 {
  font-family: var(--font-family);
  font-weight: 700;
  padding: 0.45em 0.8em;
}

/* ─── FOOTER ─────────────────────────────────────────── */
.footer {
  background-color: var(--color-bg-light);
  border-top: 1px solid #dee2e6;
}

.footer-link {
  color: var(--color-primary);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 600;
}

.footer-link:hover {
  text-decoration: underline;
  color: #0a58ca;
}

/* ─── REDUCED MOTION ─────────────────────────────────── */
/* Respects user preference for reduced motion (WCAG) */
@media (prefers-reduced-motion: reduce) {
  .memory-card .card-face,
  .memory-card,
  body,
  body[data-theme="dark"],
  body.theme-rainbow :is(.memory-card, .badge, .navbar) {
    transition: none !important;
    animation: none !important;
  }
}

/* ─── RESPONSIVE ─────────────────────────────────────── */
@media (max-width: 576px) {
  :root {
    --card-size: 72px;
    --card-radius: 8px;
  }
  .navbar-brand { font-size: 1.1rem; }
}

@media (max-width: 360px) {
  :root { --card-size: 60px; }
}