/* ================== GENERAL ================== */
html, body, #app {
  height: 100%;
  margin: 0;
}
body { overflow: hidden; font-family: sans-serif; }

/* ================== ANIMATED GRADIENT BACKGROUND ================== */
.bg-animated {
  background: linear-gradient(120deg, #ffffff, #ebebeb 50%, #f3f4f9);
  background-size: 600% 600%;
  animation: gradientShift 12s ease infinite;
}
@keyframes gradientShift {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

/* ================== FLASHCARD MODAL ================== */
#flashModal {
  position: fixed;
  inset: 0;
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 50;
  padding: 1.5rem;
}
#flashModal.active { display: flex; }

#modalBackdrop {
  position: absolute;
  inset: 0;
  background-color: rgba(0,0,0,0.5);
  backdrop-filter: blur(5px);
}

/* Modal pop animation */
.modal-content {
  transform: scale(0.8);
  opacity: 0;
  transition: all 0.3s ease-out;
}
#flashModal.active .modal-content {
  transform: scale(1);
  opacity: 1;
}

/* ================== 3D FLIP CARD ================== */
.card-3d { perspective: 1200px; }
.card-inner { transition: transform 600ms cubic-bezier(.2,.9,.3,1); transform-style: preserve-3d; }
.card-front, .card-back {
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  transform-style: preserve-3d;
  position: absolute; inset: 0;
  display: flex; align-items: center; justify-content: center;
  border-radius: 1rem; padding: 1.5rem;
  background-color: rgb(241, 232, 232);
}
.card-back { transform: rotateY(180deg); }
.card-shadow { box-shadow: 0 10px 30px rgba(2,6,23,0.2); }

/* ================== BUTTONS ================== */
button { cursor: pointer; transition: transform 0.2s ease; }
button:hover { transform: scale(1.05); }

/* ================== RESPONSIVE ================== */
@media (max-width: 768px) {
  .card-3d { max-width: 90%; height: 250px; }
}
@media (min-width: 769px) {
  .card-3d { max-width: 600px; height: 350px; }
}

/* ================== PASTEL COLOR ANIMATION ================== */
@keyframes pastelCycle {
  0%   { background-color: #cb1919; }  /* red */
  15%  { background-color: #64cb0c; }  /* green */
  30%  { background-color: #d8de20; }  /* yellow */
  45%  { background-color: #ff8da1; }  /* pink */
  60%  { background-color: #446ed1; }  /* blue */
  75%  { background-color: #ff0000; }  /* red */
  90%  { background-color: #ffa500; }  /* orange */
  100% { background-color: #ffa500; }  /* back to blue */
}

.set-color-cycle {
  color: #1f2937; /* text color: slate-800 */
  border-radius: 1rem;
  padding: 1rem;
  flex-direction: column;
  display: flex;
  justify-content: space-between;
  animation: pastelCycle 6s linear infinite;
}