https://getbootstrap.com
https://valor-software.com/ngx-bootstrap

ng add ngx-bootstrap

Create an empty file _variables.scss in src/.

If you are using bootstrap-sass, add the following to _variables.scss:

$icon-font-path: '../node_modules/bootstrap-sass/assets/fonts/bootstrap/';
//changer les couleurs de base de Bootstrap
$primary: #e83e8c;
$warning: #fd7e14;
$danger: #dc3545;

In styles.scss add the following:

@import 'variables';
@import '../node_modules/bootstrap/scss/bootstrap';

Il faut intégrer les modules utilisés dans app.module.ts

exemple :

import { BsDropdownModule } from 'ngx-bootstrap/dropdown';
...

@NgModule({
   ...
   imports: [BsDropdownModule.forRoot(), ... ],
    ...
})