diff --git a/app/src/assets/scss/base.scss b/app/src/assets/scss/base.scss
index 5937eab93..c82de79fd 100644
--- a/app/src/assets/scss/base.scss
+++ b/app/src/assets/scss/base.scss
@@ -45,8 +45,6 @@
 
 #menu & .side-panel: 7
 
-.layout--float: 999997
-
 #windowControls: 999998
 
 .b3-snackbar: 999999
diff --git a/app/src/assets/scss/business/_layout.scss b/app/src/assets/scss/business/_layout.scss
index db8f30860..9c43e21e7 100644
--- a/app/src/assets/scss/business/_layout.scss
+++ b/app/src/assets/scss/business/_layout.scss
@@ -23,7 +23,6 @@
 
   &--float {
     position: fixed;
-    z-index: 999997;
     min-height: auto;
     transition: transform .2s cubic-bezier(0, 0, .2, 1) 0ms, opacity .3s cubic-bezier(0, 0, .2, 1) 0ms;
 
diff --git a/app/src/layout/dock/index.ts b/app/src/layout/dock/index.ts
index e0a7b9658..4ffec9779 100644
--- a/app/src/layout/dock/index.ts
+++ b/app/src/layout/dock/index.ts
@@ -252,6 +252,7 @@ export class Dock {
             this.layout.element.style.opacity = "1";
         }
         this.layout.element.style.transform = "";
+        this.layout.element.style.zIndex = (++window.siyuan.zIndex).toString();
         if (this.position === "Left") {
             this.layout.element.style.left = `${this.element.clientWidth}px`;
         } else if (this.position === "Right") {