#sinp-calculator-form {
  max-width: 600px;
  background: #f9f9f9;
  border: 1px solid #dcdcdc;
  border-radius: 12px;
  padding: 25px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.05);
  font-family: "Segoe UI", sans-serif;
  margin: 20px auto;
}

#sinp-calculator-form h3 {
  margin-bottom: 15px;
  font-size: 20px;
  color: #2c3e50;
  border-bottom: 1px solid #ddd;
  padding-bottom: 5px;
}

#sinp-calculator-form label {
  display: block;
  margin-top: 15px;
  margin-bottom: 5px;
  font-weight: 600;
  color: #34495e;
}

#sinp-calculator-form select {
  width: 100%;
  padding: 10px;
  border-radius: 6px;
  border: 1px solid #ccc;
  font-size: 16px;
  background: #fff;
  box-sizing: border-box;
  transition: border 0.3s ease;
}

#sinp-calculator-form select:focus {
  border-color: #3498db;
  outline: none;
}

#sinp-calculator-form input[type="submit"] {
  margin-top: 25px;
  background-color: #27ae60;
  color: #fff;
  padding: 12px 24px;
  font-size: 16px;
  font-weight: bold;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.3s ease;
}

#sinp-calculator-form input[type="submit"]:hover {
  background-color: #219150;
}

#sinp-result {
  padding: 15px;
  background-color: #eafaf1;
  color: #2d8659;
  border: 1px solid #b6e5c6;
  border-radius: 8px;
  font-size: 18px;
  margin-top: 20px;
  text-align: center;
}