Animation and Timing

$ease-in-quad: cubic-bezier(0.550, 0.085, 0.680, 0.530);
$ease-in-cubic: cubic-bezier(0.550, 0.055, 0.675, 0.190);
$ease-in-quart: cubic-bezier(0.895, 0.030, 0.685, 0.220);
$ease-in-quint: cubic-bezier(0.755, 0.050, 0.855, 0.060);
$ease-in-sine: cubic-bezier(0.470, 0.000, 0.745, 0.715);
$ease-in-expo: cubic-bezier(0.950, 0.050, 0.795, 0.035);
$ease-in-circ: cubic-bezier(0.600, 0.040, 0.980, 0.335);
$ease-in-back: cubic-bezier(0.600, -0.280, 0.735, 0.045);

$ease-out-quad: cubic-bezier(0.250, 0.460, 0.450, 0.940);
$ease-out-cubic: cubic-bezier(0.215, 0.610, 0.355, 1.000);
$ease-out-quart: cubic-bezier(0.165, 0.840, 0.440, 1.000);
$ease-out-quint: cubic-bezier(0.230, 1.000, 0.320, 1.000);
$ease-out-sine: cubic-bezier(0.390, 0.575, 0.565, 1.000);
$ease-out-expo: cubic-bezier(0.190, 1.000, 0.220, 1.000);
$ease-out-circ: cubic-bezier(0.075, 0.820, 0.165, 1.000);
$ease-out-back: cubic-bezier(0.175, 0.885, 0.320, 1.275);

$ease-in-out-quad: cubic-bezier(0.455, 0.030, 0.515, 0.955);
$ease-in-out-cubic: cubic-bezier(0.645, 0.045, 0.355, 1.000);
$ease-in-out-quart: cubic-bezier(0.770, 0.000, 0.175, 1.000);
$ease-in-out-quint: cubic-bezier(0.860, 0.000, 0.070, 1.000);
$ease-in-out-sine: cubic-bezier(0.445, 0.050, 0.550, 0.950);
$ease-in-out-expo: cubic-bezier(1.000, 0.000, 0.000, 1.000);
$ease-in-out-circ: cubic-bezier(0.785, 0.135, 0.150, 0.860);
$ease-in-out-back: cubic-bezier(0.680, -0.550, 0.265, 1.550);

.fade-in {
  opacity: 0;
  transition: opacity 0.3s $ease-out-cubic;
  
  &.visible {
    opacity: 1;
  }
}

.slide-up {
  transform: translateY(20px);
  transition: transform 0.4s $ease-out-quart;
  
  &.animated {
    transform: translateY(0);
  }
}

.bounce-button {
  transition: transform 0.2s $ease-out-back;
  
  &:hover {
    transform: scale(1.05);
  }
  
  &:active {
    transform: scale(0.95);
    transition-timing-function: $ease-in-back;
  }
}

.modal {
  opacity: 0;
  transform: scale(0.8);
  transition: 
    opacity 0.3s $ease-out-cubic,
    transform 0.3s $ease-out-back;
  
  &.open {
    opacity: 1;
    transform: scale(1);
  }
  
  &.closing {
    transition-timing-function: $ease-in-cubic, $ease-in-back;
  }
}

.modal-backdrop {
  opacity: 0;
  transition: opacity 0.2s $ease-out-quad;
  
  &.visible {
    opacity: 1;
  }
}

.nav-item {
  position: relative;
  
  &::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: currentColor;
    transition: width 0.3s $ease-out-expo;
  }
  
  &:hover::after {
    width: 100%;
  }
}

.mobile-menu {
  transform: translateX(-100%);
  transition: transform 0.4s $ease-out-circ;
  
  &.open {
    transform: translateX(0);
  }
}

@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.1); }
}

.loading-spinner {
  animation: spin 1s $ease-in-out-cubic infinite;
}

.pulse-loader {
  animation: pulse 1.5s $ease-in-out-sine infinite;
}

.bouncing-dots {
  .dot {
    animation: bounce 1.4s $ease-in-out-back infinite;
    
    &:nth-child(1) { animation-delay: 0.0s; }
    &:nth-child(2) { animation-delay: 0.2s; }
    &:nth-child(3) { animation-delay: 0.4s; }
  }
}

@keyframes bounce {
  0%, 80%, 100% { transform: scale(0); }
  40% { transform: scale(1); }
}

.card {
  transition: 
    transform 0.3s $ease-out-quart,
    box-shadow 0.3s $ease-out-quad;
  
  &:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
  }
}

.flip-card {
  .card-inner {
    transition: transform 0.6s $ease-in-out-back;
    transform-style: preserve-3d;
  }
  
  &:hover .card-inner {
    transform: rotateY(180deg);
  }
}

.floating-label {
  .label {
    transition: all 0.2s $ease-out-cubic;
    transform-origin: left top;
  }
  
  .input:focus + .label,
  .input:not(:placeholder-shown) + .label {
    transform: translateY(-20px) scale(0.8);
  }
}

.input-underline {
  position: relative;
  
  &::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 2px;
    background-color: #3498db;
    transition: 
      width 0.3s $ease-out-expo,
      left 0.3s $ease-out-expo;
  }
  
  &:focus::after {
    width: 100%;
    left: 0;
  }
}

.gpu-accelerated {
  // Trigger hardware acceleration
  transform: translateZ(0);
  will-change: transform, opacity;
  
  // Use transform instead of changing layout properties
  transition: transform 0.3s $ease-out-cubic;
  
  &:hover {
    transform: translateY(-2px) translateZ(0);
  }
}

.animated-element {
  transition: transform 0.3s $ease-out-cubic;
  
  @media (prefers-reduced-motion: reduce) {
    transition: none;
  }
}

// Alternative: Use simpler animations for reduced motion
@media (prefers-reduced-motion: reduce) {
  .complex-animation {
    transition: opacity 0.2s ease;
  }
}

@media (prefers-reduced-motion: no-preference) {
  .complex-animation {
    transition: 
      transform 0.4s $ease-out-back,
      opacity 0.3s $ease-out-cubic,
      box-shadow 0.3s $ease-out-quad;
  }
}