body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #f5f7fa;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding: 40px 20px;
    min-height: 100vh;
  }

  .card {
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    padding: 30px 40px;
    max-width: 480px;
    width: 100%;
  }

  .section-title {
    font-size: 1.8rem;
    font-weight: 700;
    color: #222;
    margin-bottom: 25px;
    text-align: center;
  }

  input[type="text"], input[type="number"] {
    width: calc(50% - 10px);
    padding: 12px 15px;
    font-size: 1rem;
    border: 2px solid #ddd;
    border-radius: 8px;
    transition: border-color 0.3s;
    margin-top: 20px;
  }

  input[type="text"]:focus, input[type="number"]:focus {
    border-color: #0077ff;
    outline: none;
    box-shadow: 0 0 5px #0077ffaa;
  }

  #postingNumberInput {
    margin-right: 20px;
  }

  button {
    width: 100%;
    margin-top: 25px;
    background-color: #0077ff;
    color: white;
    border: none;
    padding: 14px;
    font-size: 1.1rem;
    font-weight: 600;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s;
  }

  button:hover {
    background-color: #005bb5;
  }

  #resultBlock {
    margin-top: 30px;
    background: #f0f8ff;
    border-radius: 8px;
    padding: 20px 25px;
    color: #333;
    font-size: 1.05rem;
    line-height: 1.5;
    box-shadow: inset 0 0 10px #cce4ff;
  }

  #resultBlock p {
    margin: 8px 0;
  }

  @media(max-width: 520px) {
    input[type="text"], input[type="number"] {
      width: 100%;
      margin: 0 0 15px 0 !important;
    }
  }
.tab-button {
  padding: 0.5rem 1rem;
  border: none;
  background-color: #eee;
  cursor: pointer;
  margin-right: 5px;
  border-radius: 4px;
}

.setting-button {
  padding: 0.5rem 1rem;
  border: none;
  background-color: #b3b3b3;
  cursor: pointer;
  margin-right: 5px;
  border-radius: 4px;
}

.setting-button.active {
  padding: 0.5rem 1rem;
  border: none;
  background-color: #2dd0b8;
  cursor: pointer;
  margin-right: 5px;
  border-radius: 4px;
}

.tab-button.active { 
  background-color: #007bff; 
  color: white; 
  }

.tab-content { margin-top: 1rem; }