:root {
  --primary-color: #29cc57;
  --primary-light: #e8f9ee;
  --primary-dark: #1ea848;
}

body {
  background-color: #f5f7fa;
}

.btn-primary {
  background-color: var(--primary-color);
  color: white;
  transition: all 0.3s ease;
}

.btn-primary:hover {
  background-color: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(41, 204, 87, 0.3);
}

.form-container {
  transition: all 0.5s ease;
  backface-visibility: hidden;
}

.flipped {
  transform: rotateY(180deg);
  opacity: 0;
  height: 0;
  overflow: hidden;
  position: absolute;
}

.study-icon {
  width: 100px;
  height: 100px;
  margin: 0 auto 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--primary-light);
  border-radius: 50%;
  border: 4px solid var(--primary-color);
}

.input-group {
  position: relative;
  margin-bottom: 20px;
}

.input-group input {
  width: 100%;
  padding: 12px 15px 12px 40px;
  border: 2px solid #ddd;
  border-radius: 6px;
  font-size: 14px;
  transition: all 0.3s;
}

.input-group input:focus {
  border-color: var(--primary-color);
  outline: none;
  box-shadow: 0 0 0 3px rgba(41, 204, 87, 0.2);
}

.input-icon {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: #777;
}

.tab {
  color: #666;
  cursor: pointer;
  font-weight: 500;
}

.tab.active {
  color: var(--primary-color);
  border-bottom: 2px solid var(--primary-color);
}

.floating-notebook {
  animation: float 6s ease-in-out infinite;
}

@keyframes float {
  0% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(-15px);
  }
  100% {
    transform: translateY(0px);
  }
}

.error-message {
  position: absolute;
  top: 100%;
  color: #e74c3c;
  font-size: 13px;
  display: none;
}