Componentes de Formularios Interactivos

.form-container {
  max-width: 500px;
  margin: 2rem auto;
  padding: 2rem;
  background: #fff;
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.interactive-form {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.form-group {
  position: relative;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 1rem 0;
  border: none;
  border-bottom: 2px solid #e1e5e9;
  background: transparent;
  font-size: 1rem;
  outline: none;
  transition: all 0.3s ease;
}

.form-group label {
  position: absolute;
  top: 1rem;
  left: 0;
  font-size: 1rem;
  color: #999;
  pointer-events: none;
  transition: all 0.3s ease;
}

.form-group input:focus + label,
.form-group input:valid + label,
.form-group textarea:focus + label,
.form-group textarea:valid + label {
  top: -0.5rem;
  font-size: 0.8rem;
  color: #3b82f6;
}

.form-line {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: #3b82f6;
  transition: width 0.3s ease;
}

.form-group input:focus ~ .form-line,
.form-group textarea:focus ~ .form-line {
  width: 100%;
}

.submit-btn {
  position: relative;
  padding: 1rem 2rem;
  background: #3b82f6;
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  overflow: hidden;
  transition: all 0.3s ease;
}

.submit-btn:hover {
  background: #2563eb;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.4);
}

.btn-loader {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 20px;
  height: 20px;
  border: 2px solid transparent;
  border-top: 2px solid white;
  border-radius: 50%;
  transform: translate(-50%, -50%);
  opacity: 0;
  animation: spin 1s linear infinite;
}

.submit-btn.loading .btn-loader {
  opacity: 1;
}

.submit-btn.loading span {
  opacity: 0;
}

@keyframes spin {
  0% { transform: translate(-50%, -50%) rotate(0deg); }
  100% { transform: translate(-50%, -50%) rotate(360deg); }
}