Adding images on button click along with the change of theme

Question

I am a new bie to the world of angular so rite now I have developed the below program to load the themes dynamically as shown below

my-scss-file.scss :

@import '~@angular/material/core/theming/all-theme';

@include md-core();

$primary: md-palette($md-deep-purple);
$accent: md-palette($md-amber);

$theme: md-light-theme($primary, $accent);

@include angular-material-theme($theme);

.dark-theme {
  $dark-p: md-palette($md-deep-purple, 700);
  $dark-a: md-palette($md-amber);

  $dark-t: md-dark-theme($dark-p, $dark-a);

  @include angular-material-theme($dark-t);
}

my-html-file.html :

<div [class.dark-theme]="isDarkTheme">
<button (click)="toggleTheme()">Toggle theme</button>

my-ts-file.ts :

@Component({
  selector: 'your-component-selector',
  templateUrl: './my-html-file.html',
  styleUrls: ['my-scss-file.scss']
})
export class YourComponent implements {
  // by default, if you do not want the dark theme
  private isDarkTheme = false;

  constructor() { }

  toggleTheme() {
    this.isDarkTheme = !this.isDarkTheme;
  }
}

now the output is like as shown below output of the above angular app

now my query is that along with these button i want to add images as shown below that will be shown along with button click

how the tentative image should be there

so for that i have added images folder in my project in which i have kept images now please advise where should i add the images url in my .scss file to achieve this

Images folder location in my workspace images folder location in my workspace

below is my .angular-cli.json file contents

{
  "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
  "project": {
    "name": "dynamic-material-theming"
  },
  "apps": [
    {
      "root": "src",
      "outDir": "dist",
      "assets": [
        "assets",
        "favicon.ico"
      ],
      "index": "index.html",
      "main": "main.ts",
      "polyfills": "polyfills.ts",
      "test": "test.ts",
      "tsconfig": "tsconfig.app.json",
      "testTsconfig": "tsconfig.spec.json",
      "prefix": "app",
      "styles": [
        "styles.css",
        "theme.scss"
      ],
      "scripts": [],
      "environmentSource": "environments/environment.ts",
      "environments": {
        "dev": "environments/environment.ts",
        "prod": "environments/environment.prod.ts"
      }
    }
  ],
  "e2e": {
    "protractor": {
      "config": "./protractor.conf.js"
    }
  },
  "lint": [
    {
      "project": "src/tsconfig.app.json"
    },
    {
      "project": "src/tsconfig.spec.json"
    },
    {
      "project": "e2e/tsconfig.e2e.json"
    }
  ],
  "test": {
    "karma": {
      "config": "./karma.conf.js"
    }
  },
  "defaults": {
    "styleExt": "css",
    "component": {}
  }
}