/* ============================================================
   FLIP CARDS — spelling-course
   Extracted from the grammar-course flip-cards component.
   Only the .adv-card-flippable variant and its dependencies.
   Uses existing --teal, --coral, --gold, --green, --cream,
   --border, --shadow-sm CSS variables from course.css.
   ============================================================ */

/* ── Base card (non-flippable) ─────────────────────────────── */
.adv-card {
  background: white;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 18px;
  box-shadow: var(--shadow-sm);
}

.adv-card-head {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: 'Fredoka', sans-serif;
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 8px;
}

.adv-card-icon { font-size: 1.1rem; }

.adv-card-body {
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--text-mid);
}

.adv-card-body strong {
  color: var(--text);
  font-weight: 600;
}

.adv-card-example {
  font-family: var(--mono);
  font-size: 0.84rem;
  color: var(--teal-dark);
  background: var(--teal-pale);
  padding: 6px 10px;
  border-radius: 6px;
  display: inline-block;
  margin: 4px 0;
}

/* Accent border variants */
.adv-card-teal  { border-left: 3px solid var(--teal); }
.adv-card-coral { border-left: 3px solid var(--coral); }
.adv-card-gold  { border-left: 3px solid var(--gold); }
.adv-card-green { border-left: 3px solid var(--green); }
.adv-card-slate { border-left: 3px solid #64748B; }


/* ── Flip variant ──────────────────────────────────────────── */
.adv-card-flippable {
  position: relative;
  padding: 0;                   /* faces provide their own padding */
  cursor: pointer;
  perspective: 1200px;
  min-height: 180px;
  background: transparent;
  border: none;
  box-shadow: none;
  overflow: visible;            /* let the back rotate freely */
  transition: transform 0.18s ease;
  -webkit-tap-highlight-color: transparent; /* no flash on mobile tap */
  touch-action: manipulation;              /* no 300ms delay on Android */
}
.adv-card-flippable:hover { transform: translateY(-2px); }

.adv-card-flippable .adv-card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  min-height: inherit;
  transition: transform 0.55s cubic-bezier(.4, 0, .2, 1);
  transform-style: preserve-3d;
}
.adv-card-flippable.is-flipped .adv-card-inner { transform: rotateY(180deg); }

.adv-card-flippable .adv-card-face {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  background: white;
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow-sm);
  padding: 16px 18px;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* Accent borders on faces (not the outer wrapper) */
.adv-card-flippable.adv-card-teal  .adv-card-face { border-left: 3px solid var(--teal); }
.adv-card-flippable.adv-card-coral .adv-card-face { border-left: 3px solid var(--coral); }
.adv-card-flippable.adv-card-gold  .adv-card-face { border-left: 3px solid var(--gold); }
.adv-card-flippable.adv-card-green .adv-card-face { border-left: 3px solid var(--green); }
.adv-card-flippable.adv-card-slate .adv-card-face { border-left: 3px solid #64748B; }

.adv-card-front { z-index: 2; }
.adv-card-back {
  transform: rotateY(180deg);
  background: linear-gradient(135deg, white 0%, var(--teal-pale) 100%);
  justify-content: center;
}

/* "Tap to reveal" hint — front face only, fades after first flip */
.adv-card-flippable .adv-card-front::after {
  content: '↻ Tap to reveal';
  position: absolute;
  bottom: 10px;
  right: 14px;
  font-size: 0.68rem;
  font-weight: 700;
  color: var(--teal-dark);
  font-family: 'Fredoka', sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  opacity: 0.7;
  transition: opacity 0.2s;
  pointer-events: none;
}
.adv-card-flippable:hover .adv-card-front::after { opacity: 1; }
.adv-card-flippable.has-been-flipped .adv-card-front::after {
  content: '↻ Flip back';
  opacity: 0.35;
}

/* Green ✓ "studied" badge — appears on back after first flip */
.adv-card-flippable .adv-card-back::before {
  content: '';
  position: absolute;
  top: 10px;
  right: 12px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--green);
  opacity: 0;
  transition: opacity 0.3s ease 0.3s;
  box-shadow: 0 2px 6px rgba(34, 197, 94, 0.35);
}
.adv-card-flippable .adv-card-back::after {
  content: '✓';
  position: absolute;
  top: 10px;
  right: 12px;
  width: 20px;
  height: 20px;
  color: white;
  font-size: 0.8rem;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  opacity: 0;
  transition: opacity 0.3s ease 0.3s;
  pointer-events: none;
}
.adv-card-flippable.has-been-flipped .adv-card-back::before,
.adv-card-flippable.has-been-flipped .adv-card-back::after {
  opacity: 1;
}

/* Front prompt area */
.adv-card-front .adv-card-prompt {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  font-family: 'Lora', serif;
  font-size: 0.95rem;
  line-height: 1.55;
  color: var(--text-mid);
  font-style: italic;
  padding: 4px 0 20px;
}
.adv-card-front .adv-card-prompt strong {
  display: block;
  font-style: normal;
  color: var(--text);
  font-family: 'Fredoka', sans-serif;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 6px;
}

/* Back body */
.adv-card-back .adv-card-body {
  font-size: 0.86rem;
  line-height: 1.6;
  color: var(--text-mid);
}


/* ── Keyboard accessibility ────────────────────────────────── */
.adv-card-flippable:focus-visible {
  outline: 2px solid var(--teal);
  outline-offset: 3px;
  border-radius: 14px;
}


/* ── Reduced motion ────────────────────────────────────────── */
@media (prefers-reduced-motion: reduce) {
  .adv-card-flippable .adv-card-inner { transition: none; }
  .adv-card-flippable                 { transition: none; }
  .adv-card-flippable:hover           { transform: none; }
}


/* ── Print: flatten both faces stacked ────────────────────── */
@media print {
  .adv-card-flippable             { min-height: auto; padding: 0; }
  .adv-card-flippable .adv-card-inner { transform: none !important; }
  .adv-card-flippable .adv-card-face {
    position: static;
    backface-visibility: visible;
    transform: none !important;
    margin-bottom: 8px;
  }
}