todo_app_flask/app/tasks/templates/edit_task.html

<style>
#content {
  font-size: 1.2rem;
  width: 100%;
}
form {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 100%;
}
form p {
  width: 100%;
}
h1 {
  align-self: center;
  margin-top: 50px;
}
</style>
{% extends "base.html" %}

{% block content %}
  <div class="formContainer">
    <h1>Edit {{ task.content[0:10] }}</h1>
    <form action="" method="post">
      {{ form.hidden_tag() }}
      <p>
        {{ form.content.label }}<br>
        {{ form.content(rows=20) }}<br>
        {% for error in form.content.errors %}
          <span class="formWarning">[{{ error }}]</span>
        {% endfor %}
      </p>
      <p>{{ form.submit() }}</p>
    </form>
  </div>
{% endblock %}