body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
    background: linear-gradient(to right, #f0f4ff, #f9fcff);
    color: #333;
  }
  header {
    background-color: #4a90e2;
    color: white;
    padding: 24px 16px;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  }
  header h1 {
    margin: 0;
    font-size: 28px;
  }
  .container {
    max-width: 900px;
    margin: 0 auto;
    padding: 24px;
  }
  .intro {
    margin-bottom: 32px;
    font-size: 18px;
    line-height: 1.6;
    background: #e3f2fd;
    padding: 16px;
    border-radius: 8px;
    border-left: 6px solid #4a90e2;
  }
  .step {
    margin-bottom: 40px;
  }
  .step img {
    max-width: 100%;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  }
  .step-title {
    font-size: 22px;
    margin: 16px 0 10px;
    font-weight: bold;
    color: #2c3e50;
  }
  .centered img {
    display: block;
    margin: 0 auto;
    max-width: 70%;
  }
  footer {
    text-align: center;
    font-size: 14px;
    padding: 20px;
    color: #888;
    background-color: #f0f0f0;
    margin-top: 40px;
  }
  .youtube-div {
    position: relative;
    padding-top: 56.25%; /* Tỷ lệ 16:9 */
    height: 0;
    width: 100%;
  }
  
  .youtube-iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
  }
  

  .device-table {
    max-width: 600px;
    margin: 30px auto;
    border-collapse: collapse;
    width: 100%;
    font-family: Arial, sans-serif;
    border: 1px solid #ccc;
  }

  .device-table th, .device-table td {
    border: 1px solid #ccc;
    padding: 10px;
    text-align: left;
  }

  .device-table th {
    background-color: #f2f2f2;
  }

  .device-table tfoot td {
    font-weight: bold;
    background-color: #fafafa;
  }

  /* Responsive 2 cột nếu cần, ví dụ chia đôi tên thiết bị và giá */
  .device-name {
    display: flex;
    justify-content: space-between;
  }