body {
    font-family: 'Arial', sans-serif;
    background-color: #f4f4f4;
    margin: 0;
    padding: 20px;
  }
  .container {
    max-width: 600px;
    margin: 0 auto;
    background: #fff;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
  }
  .container h2 {
    color: #333;
  }
  input[type="text"],
  input[type="number"],
  button {
    padding: 10px;
    margin-bottom: 10px;
    border-radius: 5px;
    border: 1px solid #ddd;
    width: calc(50% - 22px);
    outline: none;
  }
  button {
    width: auto;
    background-color: #5cb85c;
    color: white;
    cursor: pointer;
    border: none;
    transition: background-color 0.3s ease-in-out;
  }
  button:hover {
    background-color: #4cae4c;
  }
  .list-group {
    list-style: none;
    padding: 0;
  }
  .list-group li {
    padding: 10px;
    background-color: #efefef;
    margin-bottom: 5px;
    border-radius: 5px;
    position: relative;
  }
  .list-group li button {
    padding: 5px 10px;
    background-color: #d9534f;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    position: absolute;
    top: 50%;
    right: 10px;
    transform: translateY(-50%);
  }
  .list-group li button:hover {
    background-color: #c9302c;
  }
  #result {
    margin-top: 20px;
    font-size: 1.25em;
    color: #5cb85c;
  }