.custom-select-wrapper {
      position: relative;
      display: inline-block;
    }

    .custom-select-btn {
      background-color: #333;
      color: white;
      border: none;
      padding: 10px 16px;
      border-radius: 5px;
      cursor: pointer;
      min-width: 200px;
      text-align: left;
    }

    .converter-popup {
      position: absolute;
      top: 100%;
      left: 0;
      margin-top: 5px; /* khoảng cách nhỏ bên dưới nút */
      z-index: 999;
      width: 360px;
      background-color: #1c1c1c;
      border-radius: 10px;
      padding: 15px;
      gap: 15px;
      display: none; /* ✅ ẨN MẶC ĐỊNH */
    }

    .converter-popup.show {
      display: flex;
    }

    .sidebar {
      width: 90px;
      border-right: 1px solid #444;
      padding-right: 10px;
    }

    .sidebar ul {
      list-style: none;
      padding: 0;
      margin: 0;
    }

    .sidebar li {
      padding: 10px 5px;
      cursor: pointer;
      color: #ccc;
    }

    .sidebar li:hover,
    .sidebar li.active {
      color: #fff;
      font-weight: bold;
    }

    .content {
      flex-grow: 1;
    }

    .search-box {
      margin-bottom: 10px;
    }

    .search-box input {
      width: 100%;
      padding: 6px 8px;
      background-color: #2a2a2a;
      border: none;
      border-radius: 4px;
      color: white;
    }

    .format-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 8px;
    }

    .format-grid button {
      background-color: #333;
      color: #fff;
      border: none;
      padding: 8px 0;
      border-radius: 4px;
      cursor: pointer;
      font-weight: bold;
    }

    .format-grid button:hover {
      background-color: #555;
    }