index.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <title>Swap Demo Tutorial</title>
    <script src="https://cdn.jsdelivr.net/npm/web3@latest/dist/web3.min.js"></script>
    <script src="https://code.jquery.com/jquery-3.6.0.min.js" integrity="sha256-/xUj+3OJU5yExlq6GSYGSHk7tPXikynS7ogEvDej/m4=" crossorigin="anonymous"></script>

    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js" integrity="sha384-wfSDF2E50Y2D1uUdj0O3uMBJnjuUD4Ih7YwaYd1iqfktj0Uod8GCExl3Og8ifwB6" crossorigin="anonymous"></script>
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous">
    <link rel="stylesheet" href="./style.css">
  </head>
<body>
    <nav class="navbar navbar-expand-lg navbar-light bg-light">
        <a class="navbar-brand" href="#">My DEX Aggregator</a>
        <ul class="navbar-nav ml-auto">
          <li class="nav-item">
            <button id="login_button" class="btn btn-outline-primary my-2 my-sm-0" type="submit">Sign in with MetaMask</button>
          </li>
      </nav>
      <div class ="container">
        <div class="row">
            <div class="col col-md-6 offset-md-3" id="window">
                <h4>Swap</h4>
                <div id="form">
                    <div class="swapbox">
                        <div class="swapbox_select token_select" id="from_token_select">
                            <img class="token_img" id="from_token_img">
                            <span id="from_token_text"></span>
                        </div>
                        <div class="swapbox_select">
                            <input class="number form-control" placeholder="amount" id="from_amount">
                        </div>
                    </div>
                    <div class="swapbox">
                        <div class="swapbox_select token_select" id="to_token_select">
                            <img class="token_img" id="to_token_img">
                            <span id="to_token_text"></span>
                        </div>
                         <div class="swapbox_select">
                            <input class="number form-control" placeholder="amount" id="to_amount">
                        </div>
                    </div>  
                    <div class="gas_estimate_label">Estimated Gas: <span id="gas_estimate"></span></div>
                    <button disabled class="btn btn-large btn-primary btn-block" id="swap_button">Swap</button>                
                </div>
            </div>
        </div>
    </div>
    <div class="modal" id="token_modal" tabindex="-1" role="dialog">
      <div class="modal-dialog" role="document">
        <div class="modal-content">
          <div class="modal-header">
            <h5 class="modal-title">Select a Token</h5>
            <button id="modal_close" type="button" class="close" data-dismiss="modal" aria-label="Close">
              <span aria-hidden="true">&times;</span>
            </button>
          </div>
          <div class="modal-body">
            <div id="token_list"></div>
          </div>
        </div>
      </div>
    </div>
      <script src="./bundle.js" type="text/javascript"></script>
    </body>
</html>