fix(core): dropdown menu cannot be hovered when it is at the bottom of doc (#8662)

close AF-1588

packages/frontend/core/src/components/blocksuite/block-suite-editor/styles.css.ts

@@ -1,8 +1,6 @@
 import { cssVar } from '@toeverything/theme';
 import { style, type StyleRule } from '@vanilla-extract/css';
 
-const editorBottomPadding = 32;
-
 export const docEditorRoot = style({
   display: 'block',
   background: cssVar('backgroundPrimaryColor'),
@@ -31,13 +29,10 @@ export const docEditorGap = style({
   display: 'block',
   width: '100%',
   margin: '0 auto',
-  // hack to cover the bottom padding of the editor
-  marginTop: -editorBottomPadding,
-  paddingTop: 50 + editorBottomPadding,
+  paddingTop: 50,
   paddingBottom: 50,
   cursor: 'text',
   flexGrow: 1,
-  zIndex: 1,
 });
 
 const titleTagBasic = style({