diff --git a/src/frontend/app/attachments/attachments-page/attachment-page.component.scss b/src/frontend/app/attachments/attachments-page/attachment-page.component.scss
index 5f67ed061e2364f76588fefbdddd31c2d1ab4a23..f48e6dc4709646901e1c71190bd0de96f18f6f77 100644
--- a/src/frontend/app/attachments/attachments-page/attachment-page.component.scss
+++ b/src/frontend/app/attachments/attachments-page/attachment-page.component.scss
@@ -71,7 +71,7 @@
 
     ::ng-deep.mat-tab-header {
         position: sticky;
-        z-index: 2;
+        z-index: 1;
         height: 50px;
         background: white;
         top: 0px; 
diff --git a/src/frontend/app/viewer/document-viewer.component.html b/src/frontend/app/viewer/document-viewer.component.html
index 564d0e338bcbb877e8c977ec121f49ffd9256283..3e51000d33b825c92335d585ef4c42bf428382bc 100644
--- a/src/frontend/app/viewer/document-viewer.component.html
+++ b/src/frontend/app/viewer/document-viewer.component.html
@@ -110,7 +110,7 @@
         (triggerCloseEditor)="closeEditor()" (triggerModifiedDocument)="isDocModified = true"></onlyoffice-viewer>
 </ng-container>
 <button mat-fab *ngIf="isDocModified && mode === 'mainDocument' && resId !== null" color="accent"
-    [title]="lang.saveModifications" style="position: absolute;z-index: 1;bottom: 40px;right: 60px;"
+    [title]="lang.saveModifications" style="position: absolute;z-index: 3;bottom: 40px;right: 60px;"
     (click)="saveMainDocument()">
     <mat-icon style="height:auto;font-size:20px;" class="fas fa-check"></mat-icon>
 </button>
diff --git a/src/frontend/plugins/onlyoffice-api-js/onlyoffice-viewer.component.scss b/src/frontend/plugins/onlyoffice-api-js/onlyoffice-viewer.component.scss
index f7936e51c2a6cd2f5d47e6d5bef800000d6ac8da..7e0ff7e03f31cfb67c1ac27d65dace3600de4ec7 100644
--- a/src/frontend/plugins/onlyoffice-api-js/onlyoffice-viewer.component.scss
+++ b/src/frontend/plugins/onlyoffice-api-js/onlyoffice-viewer.component.scss
@@ -2,7 +2,7 @@
 .onlyofficeButton_fullscreen, .onlyofficeButton_close {
     position: absolute;
     top: 12px;
-    z-index: 1;
+    z-index: 3;
 }
 
 .onlyofficeButton {
diff --git a/src/frontend/plugins/onlyoffice-api-js/onlyoffice-viewer.component.ts b/src/frontend/plugins/onlyoffice-api-js/onlyoffice-viewer.component.ts
index 68812944551b638e600395119733270e851d8647..24f6d3036505621914d2e471fcf45d3ff1ea1acc 100644
--- a/src/frontend/plugins/onlyoffice-api-js/onlyoffice-viewer.component.ts
+++ b/src/frontend/plugins/onlyoffice-api-js/onlyoffice-viewer.component.ts
@@ -15,7 +15,7 @@ import { LANG } from '../../app/translate.component';
 import { ConfirmComponent } from '../modal/confirm.component';
 import { MatDialogRef, MatDialog } from '@angular/material';
 import { NotificationService } from '../../app/notification.service';
-import { HeaderService } from '../../service/header.service.js';
+import { HeaderService } from '../../service/header.service';
 
 declare var DocsAPI: any;
 declare function $j(selector: any): any;
@@ -314,11 +314,13 @@ export class EcplOnlyofficeViewerComponent implements OnInit, AfterViewInit {
                 this.headerService.sideNavLeft.close();
             }
             $j("iframe[name='frameEditor']").css("position", "fixed");
+            $j("iframe[name='frameEditor']").css("z-index", "2");
         } else {
             if (this.headerService.sideNavLeft !== null) {
                 this.headerService.sideNavLeft.open();
             }
             $j("iframe[name='frameEditor']").css("position", "initial");
+            $j("iframe[name='frameEditor']").css("z-index", "1");
         }
         this.fullscreenMode = !this.fullscreenMode;
     }