title: ngx-gallery not displaying left-right arrow over image in Angular
body: <p>I am using ngx-gallery to display an image gallery. Although I set the display image arrow property to be true, I can't see the arrows in the image.</p>
  
  <p>I am using Angular 7. This is my gallery.ts file code:</p>
  
  <pre><code> galleryOptions: NgxGalleryOptions[];
    galleryImages: NgxGalleryImage[];
  
    ngOnInit(): void {
  
        this.galleryOptions = [
            {
                'previewCloseOnEsc': true,
                'previewKeyboardNavigation': true,
                'imageBullets': true,
                'imageAutoPlay': true,
                width: '100%',
                height: '400px',
                thumbnailsColumns: 4,
                imageAnimation: NgxGalleryAnimation.Slide
            },
            // max-width 800
            {
                breakpoint: 800,
                width: '100%',
                height: '600px',
                imagePercent: 90,
                thumbnailsPercent: 10,
                thumbnailsMargin: 20,
                thumbnailMargin: 20
            },
            // max-width 400
            {
                breakpoint: 400,
                preview: false
            }
        ];
  
        this.galleryImages = [
            {
                small: 'assets/1-small.png',
                medium: 'assets/1-medium.png',
                big: 'assets/1-big.png'
            },
            {
                small: 'assets/2-small.png',
                medium: 'assets/2-medium.png',
                big: 'assets/2-big.png'
            },
            {
                small: 'assets/3-small.png',
                medium: 'assets/3-medium.png',
                big: 'assets/3-big.png'
            },
            {
              small: 'assets/4-small.png',
              medium: 'assets/4-medium.png',
              big: 'assets/4-big.png'
          }
        ];
    }
  </code></pre>
  
  <p>I have also changed the css as described in some forum:</p>
  
  <pre><code>ngx-gallery /deep/ ngx-gallery-image .ngx-gallery-arrow {
    background-color: orangered;
  }
  ngx-gallery /deep/ ngx-gallery-thumbnails .ngx-gallery-arrow {
    background-color: orangered;
  }
  ngx-gallery /deep/ ngx-gallery-preview .ngx-gallery-arrow {
    background-color: orangered;
  }
  </code></pre>
  
  <p>This is my gallery.html code</p>
  
  <pre><code>&lt;ngx-gallery [options]="galleryOptions" [images]="galleryImages"&gt;&lt;/ngx-gallery&gt;
  </code></pre>