Wrapping a class around @important rule in scss is not working

Question

In my app.vue I want to include bootstrap.css but with a scoped wrapper.

<style lang="scss"> 
#voucher-mailing-vue-wrapper {
    @import "~bootstrap/scss/bootstrap.scss";
    @import "~bootstrap-vue/src/index.scss";
}
@import "styles/app";
</style>

When I watch it in chrome you can see that the first import for the css is empty but the second import for bootstrap-vue seems to work.

         <style type="text/css">#voucher-mailing-vue-wrapper {
          /*!
         * Bootstrap v4.4.1 (https://getbootstrap.com/)
         * Copyright 2011-2019 The Bootstrap Authors
         * Copyright 2011-2019 Twitter, Inc.
         * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
         */
    **HERE SHOULD THE BOOTSTRAP FILES BE INCLUDED** 
        }
        </style>

<style type="text/css">#voucher-mailing-vue-wrapper {
#voucher-mailing-vue-wrapper :root {
    --blue: #007bff;
    --indigo: #6610f2;
    --purple: #6f42c1;
    --pink: #e83e8c;
    --red: #dc3545;
    --orange: #fd7e14;
    --yellow: #ffc107;
    --green: #28a745;
    --teal: #20c997;
    --cyan: #17a2b8;
    --white: #fff;
    --gray: #6c757d;
    --gray-dark: #343a40;
    --primary: #007bff;
    --secondary: #6c757d;
    --success: #28a745;
    --info: #17a2b8;
    --warning: #ffc107;
    --danger: #dc3545;
    --light: #f8f9fa;
    --dark: #343a40;
    --breakpoint-xs: 0;
    --breakpoint-sm: 576px;
    --breakpoint-md: 768px;
    --breakpoint-lg: 992px;
    --breakpoint-xl: 1200px;
    --font-family-sans-serif: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
    --font-family-monospace: SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
}
#voucher-mailing-vue-wrapper *,
  #voucher-mailing-vue-wrapper *::before,
  #voucher-mailing-vue-wrapper *::after {
    -webkit-box-sizing: border-box;
            box-sizing: border-box;
}
#voucher-mailing-vue-wrapper html {
    font-family: sans-serif;
    line-height: 1.15;
    -webkit-text-size-adjust: 100%;
    -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
}
</style>

What is wrong here ? As I read some other answers regarding to bootstrap, vue and imports, it should be fine this way?

Thanks in advance.

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