alfresco-ng2-components/lib/core/viewer/components/imgViewer.component.scss

@mixin adf-image-viewer-theme($theme) {
    $background: map-get($theme, background);

    .adf-image-viewer {
        .adf-image-container {
            display: flex;
            flex: 1;
            text-align: center;
            flex-direction: row;
            justify-content: center;
            height: 90vh;
            img {
                width: 100%;
                object-fit: contain;
            }
        }

        &__toolbar {
            position: absolute;
            bottom: 5px;

            left: 50%;
            transform: translateX(-50%);

            .adf-toolbar .mat-toolbar {
                max-height: 48px;
                background-color: mat-color($background, card);
                border-width: 0;
                border-radius: 2px;
                box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.24), 0 0 2px 0 rgba(0, 0, 0, 0.12);
            }

        }
    }
}