Bootstrap 4 NgBootstrap分级呈现屏幕阅读器元素

我正在尝试在我的项目中使用NgBootstrap评级系统。我遇到的问题是评级系统正在渲染屏幕阅读器元素（见上图）

在我的组件中，标记如下所示

<ngb-rating [rate]="3"></ngb-rating>

如何确保屏幕阅读器元素不渲染？

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你能试着提供一个最小的复制场景吗？我在演示页面上看不到此效果：。你可以从一个分叉的堆栈闪电战开始：如果我不得不猜测的话，我会说引导CSS没有被正确地包括在内（

sru-only

元素应该是DOM的一部分，但是被CSS隐藏）。

{
  "name": "fancy-app",
  "version": "0.0.0",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },
  "private": true,
  "dependencies": {
    "@agm/core": "^1.0.0-beta.3",
    "@angular/animations": "^6.0.3",
    "@angular/common": "^6.0.3",
    "@angular/compiler": "^6.0.3",
    "@angular/core": "^6.0.3",
    "@angular/forms": "^6.0.3",
    "@angular/http": "^6.0.3",
    "@angular/platform-browser": "^6.0.3",
    "@angular/platform-browser-dynamic": "^6.0.3",
    "@angular/router": "^6.0.3",
    "@ng-bootstrap/ng-bootstrap": "^2.1.2",
    "@types/googlemaps": "^3.30.10",
    "angular2-google-map-auto-complete": "^2.0.9",
    "bootstrap": "^4.1.1",
    "core-js": "^2.5.4",
    "lodash": "^4.17.10",
    "rxjs": "^6.0.0",
    "zone.js": "^0.8.26"
  },
  "devDependencies": {
    "@angular/compiler-cli": "^6.0.3",
    "@angular-devkit/build-angular": "~0.6.8",
    "typescript": "~2.7.2",
    "@angular/cli": "~6.0.8",
    "@angular/language-service": "^6.0.3",
    "@types/jasmine": "~2.8.6",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "~8.9.4",
    "codelyzer": "~4.2.1",
    "jasmine-core": "~2.99.1",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~1.7.1",
    "karma-chrome-launcher": "~2.2.0",
    "karma-coverage-istanbul-reporter": "~2.0.0",
    "karma-jasmine": "~1.1.1",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.3.0",
    "ts-node": "~5.0.1",
    "tslint": "~5.9.1"
  }
}