main.html

<!DOCTYPE html>
<html lang="en" dir="ltr">
  <head>
    <meta charset="utf-8">
    <title>Tom's Todo List</title>
    <link type="text/css" rel="stylesheet" href="main.css" />
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
  </head>
  <body>
    <div id="container">
        <h1>Tom's Todo List</h1>
        <div>
          <div id="tasks">
              <div class="task">
                  <input type="checkbox">
                  <label class="taskLabel">Finish web app</label>
                  <button class="deleteTask">X</button>
              </div>
          </div>
          <div id="newTask">
            <input id="newTaskContent" type="textbox" placeholder="Add a new task..." style="width: 100%">
            <button id="addTask">add</button>
          </div>
        </div>
    </div>
    <script src="main.js"></script>
  </body>
</html>