body {
  background-color: #f3f4f6;
}
input[type="number"] {
  transition: border-color 0.3s ease;
}
input[type="number"]:focus {
  border-color: #2563eb;
  outline: none;
}
button {
  transition: background-color 0.3s ease;
}
#results .ratio-card {
  background-color: #f9fafb;
  border-radius: 8px;
  padding: 1rem;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}
#investmentRecommendation .invest-box {
  background-color: #e5e7eb;
  border-radius: 8px;
  padding: 1rem;
}
@media (max-width: 640px) {
  h1 {
    font-size: 1.5rem;
  }
  h2 {
    font-size: 1.25rem;
  }
  button {
    width: 100%;
    margin-bottom: 0.5rem;
  }
  .flex {
    flex-direction: column;
  }
}