/* ===== Keyframe Animations ===== */

@keyframes fadeSlideUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeSlideDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.9);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes slideLeft {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes slideRight {
  from {
    opacity: 0;
    transform: translateX(-30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  10%, 30%, 50%, 70%, 90% { transform: translateX(-4px); }
  20%, 40%, 60%, 80% { transform: translateX(4px); }
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.05); }
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

@keyframes gradientShift {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

@keyframes toastIn {
  from {
    transform: translateX(100%) translateY(0);
    opacity: 0;
  }
  to {
    transform: translateX(0) translateY(0);
    opacity: 1;
  }
}

@keyframes toastOut {
  from {
    opacity: 1;
    transform: translateX(0);
  }
  to {
    opacity: 0;
    transform: translateX(100%);
  }
}

@keyframes countUp {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes sparkle {
  0%, 100% { opacity: 0; transform: scale(0); }
  50% { opacity: 1; transform: scale(1); }
}

@keyframes confettiFall {
  0% {
    transform: translateY(-100%) rotate(0deg);
    opacity: 1;
  }
  100% {
    transform: translateY(100vh) rotate(720deg);
    opacity: 0;
  }
}

@keyframes progressFill {
  from { width: 0; }
}

@keyframes dashAnimation {
  to { stroke-dashoffset: 0; }
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

@keyframes ripple {
  to {
    transform: scale(4);
    opacity: 0;
  }
}

@keyframes shimmer {
  0% { background-position: -200% 0; }
  100% { background-position: 200% 0; }
}

@keyframes subtleBounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-3px); }
}

@keyframes glowPulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(26, 86, 219, 0.2); }
  50% { box-shadow: 0 0 0 8px rgba(26, 86, 219, 0); }
}

@keyframes numberPop {
  0% { transform: scale(0.8); opacity: 0; }
  50% { transform: scale(1.1); }
  100% { transform: scale(1); opacity: 1; }
}

/* ===== Scroll Reveal Classes ===== */

.js-ready .reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

.js-ready .reveal-left {
  opacity: 0;
  transform: translateX(-30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal-left.visible {
  opacity: 1;
  transform: translateX(0);
}

.js-ready .reveal-right {
  opacity: 0;
  transform: translateX(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal-right.visible {
  opacity: 1;
  transform: translateX(0);
}

.js-ready .reveal-scale {
  opacity: 0;
  transform: scale(0.9);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal-scale.visible {
  opacity: 1;
  transform: scale(1);
}

/* Stagger delays for children */
.stagger > :nth-child(1) { transition-delay: 0ms; }
.stagger > :nth-child(2) { transition-delay: 80ms; }
.stagger > :nth-child(3) { transition-delay: 160ms; }
.stagger > :nth-child(4) { transition-delay: 240ms; }
.stagger > :nth-child(5) { transition-delay: 320ms; }
.stagger > :nth-child(6) { transition-delay: 400ms; }
.stagger > :nth-child(7) { transition-delay: 480ms; }
.stagger > :nth-child(8) { transition-delay: 560ms; }
.stagger > :nth-child(9) { transition-delay: 640ms; }

/* ===== Hero Animation ===== */

.hero {
  background: linear-gradient(-45deg, #1e3a5f, #1a56db, #2563eb, #7c3aed);
  background-size: 300% 300%;
  animation: gradientShift 20s ease infinite;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(2px 2px at 20% 30%, rgba(255,255,255,0.15), transparent),
    radial-gradient(2px 2px at 40% 70%, rgba(255,255,255,0.1), transparent),
    radial-gradient(2px 2px at 60% 40%, rgba(255,255,255,0.08), transparent),
    radial-gradient(2px 2px at 80% 20%, rgba(255,255,255,0.1), transparent),
    radial-gradient(3px 3px at 10% 60%, rgba(255,255,255,0.06), transparent),
    radial-gradient(2px 2px at 90% 80%, rgba(255,255,255,0.08), transparent);
  animation: float 8s ease-in-out infinite;
}

/* Subtle mesh overlay for hero depth */
.hero::after {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 30% 50%, rgba(255,255,255,0.06) 0%, transparent 70%);
  pointer-events: none;
}

/* ===== Card Hover ===== */

.card-animated {
  transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.card-animated:hover {
  transform: translateY(-4px) scale(1.02);
  box-shadow: var(--shadow-xl);
}

/* ===== Flip card for flashcards ===== */

.flip-card {
  perspective: 1000px;
  width: 100%;
  max-width: 500px;
  height: 320px;
  cursor: pointer;
}

.flip-card__inner {
  position: relative;
  width: 100%;
  height: 100%;
  transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  transform-style: preserve-3d;
}

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

.flip-card__front,
.flip-card__back {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-2xl);
  border-radius: var(--radius-xl);
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  text-align: center;
}

.flip-card__back {
  transform: rotateY(180deg);
  background: var(--color-primary-bg);
  border-color: var(--color-primary);
}

/* ===== Quiz transitions ===== */

.quiz-question-enter {
  animation: slideLeft 0.3s ease forwards;
}

.quiz-question-exit {
  animation: slideRight 0.3s ease forwards;
  position: absolute;
}

.answer-shake {
  animation: shake 0.5s ease;
}

.answer-pulse {
  animation: pulse 0.3s ease;
}

/* ===== Confetti container ===== */

.confetti-container {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 9999;
  overflow: hidden;
}

.confetti-piece {
  position: absolute;
  top: -10px;
  width: 10px;
  height: 10px;
  animation: confettiFall 3s ease-out forwards;
}

/* ===== SVG Progress Ring ===== */

.progress-ring {
  transform: rotate(-90deg);
}

.progress-ring__circle {
  transition: stroke-dashoffset 1s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===== Counter animation ===== */

.counter {
  display: inline-block;
}

.counter.animating {
  animation: countUp 0.3s ease;
}

/* ===== Mastery stars ===== */

.mastery-stars {
  display: flex;
  gap: 2px;
}

.mastery-star {
  width: 16px;
  height: 16px;
  color: var(--color-border);
  transition: all var(--transition-base);
}

.mastery-star.filled {
  color: var(--color-warning);
}

.mastery-star.new {
  animation: sparkle 0.6s ease;
}

/* ===== Swipe animation for flashcards ===== */

.swipe-left {
  animation: 0.3s ease forwards;
  animation-name: swipeLeft;
}

.swipe-right {
  animation: 0.3s ease forwards;
  animation-name: swipeRight;
}

@keyframes swipeLeft {
  to {
    transform: translateX(-120%) rotate(-15deg);
    opacity: 0;
  }
}

@keyframes swipeRight {
  to {
    transform: translateX(120%) rotate(15deg);
    opacity: 0;
  }
}

/* Card stack visual */
.card-stack {
  position: relative;
  width: 100%;
  max-width: 500px;
  height: 320px;
  margin: 0 auto;
}

.card-stack__card {
  position: absolute;
  inset: 0;
  transition: all var(--transition-base);
}

.card-stack__card:nth-child(2) {
  transform: translateY(6px) scale(0.97);
  opacity: 0.7;
}

.card-stack__card:nth-child(3) {
  transform: translateY(12px) scale(0.94);
  opacity: 0.4;
}

/* ===== Mobile Performance Optimizations ===== */

@media (max-width: 768px) {
  .hero {
    background-size: 200% 200%;
    animation-duration: 25s;
  }

  .hero::before {
    animation: none;
  }

  .reveal,
  .reveal-left,
  .reveal-right,
  .reveal-scale {
    transition-duration: 0.3s;
  }

  .card-animated:hover {
    transform: none;
    box-shadow: none;
  }

  .flip-card {
    height: min(320px, 50svh);
  }

  .card-stack {
    height: min(320px, 50svh);
  }
}

/* ===== Swipe Indicators ===== */
.swipe-indicator {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  font-weight: var(--weight-bold);
  pointer-events: none;
  transition: opacity 0.1s ease;
  z-index: 10;
}

.swipe-indicator--left {
  right: var(--space-md);
  background: var(--color-danger-bg);
  color: var(--color-danger);
  border: 2px solid var(--color-danger);
}

.swipe-indicator--right {
  left: var(--space-md);
  background: var(--color-accent-bg);
  color: var(--color-accent-dark);
  border: 2px solid var(--color-accent);
}

/* ===== Reduced motion ===== */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .reveal,
  .reveal-left,
  .reveal-right,
  .reveal-scale {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .hero {
    animation: none;
    background-position: 0% 50%;
  }
}