body {
        font-family: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN",
          "Hiragino Sans", Meiryo, sans-serif;
        margin: 0;
        padding: 0;
        background-color: #f8f9fa;
        color: #333;
        line-height: 1.6;
      }

      .main-wrapper {
        padding-top: 56px;
      }

      .container {
        display: flex;
        min-height: calc(100vh - 56px);
        flex-direction: row;
      }

      .left-panel {
        width: 280px;
        background-color: #ffffff;
        border-right: 1px solid #dee2e6;
        padding: 20px;
        box-shadow: 1px 0 5px rgba(0, 0, 0, 0.05);
        display: flex;
        flex-direction: column;
        overflow-y: auto;
      }

      .history-header {
        display: flex;
        justify-content: space-between;
        align-items: center;
        margin-bottom: 15px;
        border-bottom: 1px solid #eee;
        padding-bottom: 10px;
      }

      .history-header h3 {
        font-size: 1.1em;
        margin: 0;
        color: #495057;
      }

      #clear-history-button {
        background-color: #dc3545;
        color: white;
        border: none;
        padding: 5px 10px;
        border-radius: 4px;
        cursor: pointer;
        font-size: 0.8em;
        transition: background-color 0.2s ease;
      }

      #clear-history-button:hover {
        background-color: #c82333;
      }

      .history-container ul {
        list-style: none;
        padding: 0;
        margin: 0;
        flex-grow: 1;
      }

      .history-container li {
        background: #f1f3f5;
        margin-bottom: 8px;
        padding: 10px 12px;
        border-radius: 5px;
        font-size: 0.9em;
        border: 1px solid #e9ecef;
        transition: background-color 0.2s ease;
      }

      .history-container li:hover {
        background-color: #e9ecef;
      }

      .history-container li strong {
        display: block;
        font-size: 0.85em;
        color: #6c757d;
        margin-bottom: 4px;
      }

      .history-container li .title {
        font-weight: 600;
        color: #0056b3;
        display: block;
        margin-bottom: 2px;
      }

      .history-container li .channel {
        font-style: normal;
        color: #5a6268;
        font-size: 0.9em;
        display: block;
        margin-bottom: 5px;
      }

      .history-container li .history-link {
        font-size: 0.9em;
        color: #28a745;
        text-decoration: none;
        font-weight: 500;
      }

      .history-container li .history-link:hover {
        text-decoration: underline;
        color: #218838;
      }

      .history-container li .raw-input {
        color: #495057;
        font-style: italic;
      }

      .right-panel {
        flex-grow: 1;
        padding: 30px 40px;
        display: flex;
        flex-direction: column;
        overflow-y: auto;
      }

      .right-panel h1 {
        font-size: 2em;
        margin-bottom: 10px;
        color: #343a40;
        font-weight: 600;
      }

      .right-panel .subtitle {
        font-size: 1.1em;
        color: #6c757d;
        margin-bottom: 30px;
      }

      .feature-banner {
        background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        color: white;
        padding: 20px;
        border-radius: 8px;
        margin-bottom: 30px;
        text-align: center;
        box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
      }

      .feature-banner h3 {
        margin: 0 0 10px 0;
        font-size: 1.3em;
      }

      .feature-banner p {
        margin: 0 0 15px 0;
        opacity: 0.9;
      }

      .feature-banner .banner-btn {
        background: rgba(255, 255, 255, 0.2);
        color: white;
        padding: 10px 20px;
        border: 1px solid rgba(255, 255, 255, 0.3);
        border-radius: 25px;
        text-decoration: none;
        display: inline-block;
        transition: all 0.3s ease;
        font-weight: 500;
      }

      .feature-banner .banner-btn:hover {
        background: rgba(255, 255, 255, 0.3);
        transform: translateY(-1px);
      }

      .right-panel h3 {
        font-size: 1.3em;
        margin-bottom: 15px;
        color: #495057;
        font-weight: 500;
        border-bottom: 1px solid #eee;
        padding-bottom: 8px;
      }

      .search-section {
        margin-bottom: 30px;
      }

      .right-panel form {
        margin-top: 10px;
      }

      .right-panel input[type="text"] {
        width: 100%;
        max-width: 450px;
        padding: 12px 15px;
        border: 1px solid #ced4da;
        border-radius: 4px;
        font-size: 1em;
        margin-bottom: 15px;
        box-sizing: border-box;
      }

      .right-panel button[type="submit"] {
        padding: 12px 25px;
        font-size: 1em;
        color: #fff;
        background-color: #007bff;
        border: none;
        border-radius: 4px;
        cursor: pointer;
        transition: background-color 0.2s ease;
      }

      .right-panel button[type="submit"]:hover {
        background-color: #0056b3;
      }

      .support-section {
        margin-top: 20px;
        padding-top: 15px;
        border-top: 1px solid #eee;
      }

      .support-section h4 {
        margin-top: 0;
        margin-bottom: 8px;
        font-size: 1em;
      }

      .support-section p {
        font-size: 0.9em;
        margin-bottom: 10px;
        color: #555;
      }

      .support-section a {
        background-color: #ffc107;
        color: #212529;
        display: inline-block;
        text-decoration: none;
        padding: 10px 20px;
        border-radius: 4px;
        transition: background-color 0.2s ease;
      }

      .support-section a:hover {
        background-color: #e0a800;
      }

      .feedback-link {
        margin-top: auto;
        padding-top: 20px;
        border-top: 1px solid #eee;
        font-size: 0.9em;
        color: #6c757d;
      }

      .feedback-link a {
        color: #007bff;
        text-decoration: none;
      }

      .feedback-link a:hover {
        text-decoration: underline;
      }

      .prefill-message {
        margin-top: 15px;
        font-size: 1em;
        font-weight: bold;
        color: #17a2b8;
        background-color: #e2f6f8;
        padding: 10px;
        border-radius: 4px;
        border: 1px solid #bdedf3;
        display: inline-block;
      }

      @media (max-width: 768px) {
        .container {
          flex-direction: column;
        }

        .left-panel {
          width: 100%;
          border-right: none;
          border-bottom: 1px solid #dee2e6;
          max-height: 300px;
          box-shadow: 0 1px 5px rgba(0, 0, 0, 0.05);
          box-sizing: border-box;
        }

        .right-panel {
          padding: 20px;
        }

        .right-panel h1 {
          font-size: 1.5em;
        }

        .right-panel .subtitle {
          font-size: 1em;
          margin-bottom: 20px;
        }

        .right-panel h3 {
          font-size: 1.1em;
        }

        .right-panel input[type="text"] {
          max-width: none;
        }

        .feedback-link {
          margin-top: 30px;
        }
      }