Existing Dash app, need to add Dash Bootstrap Components

I started using DASH few months back and working on an application. I found DASH very easy to learn and implement. But now I am stuck, when i learnt about Dash Bootstrap components.

Note: I am totally new to CSS, Bootstrap etc. and using default style as (external_stylesheets = [‘https://codepen.io/chriddyp/pen/bWLwgP.css’]).

I use a file app.py, imported in all of my multi-page application, with above stylesheet.
As I am trying to use bootstrap theme, my complete layout has become small, and look of components (TABS, Links, Buttons, Font of texts) has completely changed and not looking pretty.

I am unable to switch to Dash Bootstrap because of this reason. Kindly help

  1. How can I use benefits of both stylesheets.

  2. How to decide if bootstrap be applicable to only one page, out of multi-page application.