diff --git a/packages/core/src/block/base/format.ts b/packages/core/src/block/base/format.ts
index 0d882d9..f9f8b41 100644
--- a/packages/core/src/block/base/format.ts
+++ b/packages/core/src/block/base/format.ts
@@ -26,6 +26,7 @@ import logger from '../../utils/logger';
 import type AtxHeading from '../commonMark/atxHeading';
 import type BulletList from '../commonMark/bulletList';
 import type SetextHeading from '../commonMark/setextHeading';
+import type { Nullable } from '../../types';
 import type Parent from './parent';
 
 interface IOffset {
@@ -228,7 +229,7 @@ class Format extends Content {
         text: string,
         offset: number,
         type: Token['type'],
-    ): Token | null {
+    ): Nullable<Token> {
         const tokens = tokenizer(text, {
             hasBeginRules: false,
             options: this.muya.options,
@@ -436,7 +437,7 @@ class Format extends Content {
 
         const selector = `#${imageId.includes('_') ? imageId : `${imageId}_${token.range.start}`
       } img`;
-        const image: HTMLImageElement | null = document.querySelector(selector);
+        const image: Nullable<HTMLElement> = document.querySelector<HTMLElement>(selector);
 
         if (image)
             image.click();
diff --git a/packages/core/src/block/base/linkedList/__tests__/linkedlist.spec.ts b/packages/core/src/block/base/linkedList/__tests__/linkedlist.spec.ts
index 5301426..8a088a4 100644
--- a/packages/core/src/block/base/linkedList/__tests__/linkedlist.spec.ts
+++ b/packages/core/src/block/base/linkedList/__tests__/linkedlist.spec.ts
@@ -1,6 +1,6 @@
 import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 
-import LinkedList from '../linkedList';
+import { LinkedList } from '../linkedList';
 import type { ILinkedNode } from '../linkedNode';
 import type { Nullable } from '../../../../types';
 
diff --git a/packages/core/src/block/base/linkedList/linkedList.ts b/packages/core/src/block/base/linkedList/linkedList.ts
index 1545b23..4720e86 100644
--- a/packages/core/src/block/base/linkedList/linkedList.ts
+++ b/packages/core/src/block/base/linkedList/linkedList.ts
@@ -1,7 +1,7 @@
 import type { Nullable } from '../../../types';
 import type { ILinkedNode } from './linkedNode';
 
-class LinkedList<T extends ILinkedNode> {
+export class LinkedList<T extends ILinkedNode> {
     head: Nullable<T> = null;
 
     tail: Nullable<T> = null;
@@ -118,5 +118,3 @@ class LinkedList<T extends ILinkedNode> {
         return [...this.iterator()].reduce(callback, memo);
     }
 }
-
-export default LinkedList;
diff --git a/packages/core/src/block/base/parent.ts b/packages/core/src/block/base/parent.ts
index be888b8..644ac02 100644
--- a/packages/core/src/block/base/parent.ts
+++ b/packages/core/src/block/base/parent.ts
@@ -1,4 +1,4 @@
-import LinkedList from '../../block/base/linkedList/linkedList';
+import { LinkedList } from '../../block/base/linkedList/linkedList';
 import TreeNode from '../../block/base/treeNode';
 import { CLASS_NAMES } from '../../config';
 import type { TState } from '../../state/types';
diff --git a/packages/core/src/block/base/treeNode.ts b/packages/core/src/block/base/treeNode.ts
index e7a8b77..571e938 100644
--- a/packages/core/src/block/base/treeNode.ts
+++ b/packages/core/src/block/base/treeNode.ts
@@ -174,7 +174,7 @@ class TreeNode implements ILinkedNode {
      * Find the closest block which blockName is `blockName`. return `null` if not found.
      * @param {string} blockName
      */
-    closestBlock(blockName: string): TreeNode | null {
+    closestBlock(blockName: string): Nullable<TreeNode> {
         if (this.blockName === blockName)
             return this;
 
@@ -190,7 +190,7 @@ class TreeNode implements ILinkedNode {
         return null;
     }
 
-    farthestBlock(blockName: string): TreeNode | null {
+    farthestBlock(blockName: string): Nullable<TreeNode> {
         const results: TreeNode[] = [];
         if (this.blockName === blockName)
             results.push(this);
diff --git a/packages/core/src/block/commonMark/bulletList/index.ts b/packages/core/src/block/commonMark/bulletList/index.ts
index 0aa7846..77647df 100644
--- a/packages/core/src/block/commonMark/bulletList/index.ts
+++ b/packages/core/src/block/commonMark/bulletList/index.ts
@@ -1,4 +1,4 @@
-import LinkedList from '../../base/linkedList/linkedList';
+import { LinkedList } from '../../base/linkedList/linkedList';
 import Parent from '../../base/parent';
 import IContainerQueryBlock from '../../mixins/containerQueryBlock';
 import { ScrollPage } from '../../scrollPage';
diff --git a/packages/core/src/block/commonMark/listItem/index.ts b/packages/core/src/block/commonMark/listItem/index.ts
index 25d0787..ae60f48 100644
--- a/packages/core/src/block/commonMark/listItem/index.ts
+++ b/packages/core/src/block/commonMark/listItem/index.ts
@@ -1,4 +1,4 @@
-import LinkedList from '../../base/linkedList/linkedList';
+import { LinkedList } from '../../base/linkedList/linkedList';
 import Parent from '../../base/parent';
 import IContainerQueryBlock from '../../mixins/containerQueryBlock';
 import { ScrollPage } from '../../scrollPage';
diff --git a/packages/core/src/block/commonMark/orderList/index.ts b/packages/core/src/block/commonMark/orderList/index.ts
index ceb0bb7..f9cc611 100644
--- a/packages/core/src/block/commonMark/orderList/index.ts
+++ b/packages/core/src/block/commonMark/orderList/index.ts
@@ -1,4 +1,4 @@
-import LinkedList from '../../base/linkedList/linkedList';
+import { LinkedList } from '../../base/linkedList/linkedList';
 import Parent from '../../base/parent';
 import IContainerQueryBlock from '../../mixins/containerQueryBlock';
 import { ScrollPage } from '../../scrollPage';
diff --git a/packages/core/src/block/gfm/table/cell.ts b/packages/core/src/block/gfm/table/cell.ts
index 6a9eb86..65a59fa 100644
--- a/packages/core/src/block/gfm/table/cell.ts
+++ b/packages/core/src/block/gfm/table/cell.ts
@@ -1,4 +1,4 @@
-import LinkedList from '../../base/linkedList/linkedList';
+import { LinkedList } from '../../base/linkedList/linkedList';
 import Parent from '../../base/parent';
 import type TableCellContent from '../../content/tableCell';
 import LeafQueryBlock from '../../mixins/leafQueryBlock';
diff --git a/packages/core/src/block/gfm/table/index.ts b/packages/core/src/block/gfm/table/index.ts
index 1b9335f..df47805 100644
--- a/packages/core/src/block/gfm/table/index.ts
+++ b/packages/core/src/block/gfm/table/index.ts
@@ -1,5 +1,5 @@
 import diff from 'fast-diff';
-import LinkedList from '../../base/linkedList/linkedList';
+import { LinkedList } from '../../base/linkedList/linkedList';
 import Parent from '../../base/parent';
 import type TableCellContent from '../../content/tableCell';
 import { ScrollPage } from '../../scrollPage';
diff --git a/packages/core/src/block/gfm/table/row.ts b/packages/core/src/block/gfm/table/row.ts
index d57f08e..f108932 100644
--- a/packages/core/src/block/gfm/table/row.ts
+++ b/packages/core/src/block/gfm/table/row.ts
@@ -1,4 +1,4 @@
-import LinkedList from '../../base/linkedList/linkedList';
+import { LinkedList } from '../../base/linkedList/linkedList';
 import Parent from '../../base/parent';
 import IContainerQueryBlock from '../../mixins/containerQueryBlock';
 import { ScrollPage } from '../../scrollPage';
diff --git a/packages/core/src/block/gfm/table/table.ts b/packages/core/src/block/gfm/table/table.ts
index a648e24..4926035 100644
--- a/packages/core/src/block/gfm/table/table.ts
+++ b/packages/core/src/block/gfm/table/table.ts
@@ -1,4 +1,4 @@
-import LinkedList from '../../base/linkedList/linkedList';
+import { LinkedList } from '../../base/linkedList/linkedList';
 import Parent from '../../base/parent';
 import IContainerQueryBlock from '../../mixins/containerQueryBlock';
 import { ScrollPage } from '../../scrollPage';
diff --git a/packages/core/src/block/gfm/taskListItem/index.ts b/packages/core/src/block/gfm/taskListItem/index.ts
index 93974a9..db1b53a 100644
--- a/packages/core/src/block/gfm/taskListItem/index.ts
+++ b/packages/core/src/block/gfm/taskListItem/index.ts
@@ -1,4 +1,4 @@
-import LinkedList from '../../base/linkedList/linkedList';
+import { LinkedList } from '../../base/linkedList/linkedList';
 import Parent from '../../base/parent';
 import IContainerQueryBlock from '../../mixins/containerQueryBlock';
 import { ScrollPage } from '../../scrollPage';
diff --git a/packages/core/src/selection/index.ts b/packages/core/src/selection/index.ts
index 39251fe..b29969c 100644
--- a/packages/core/src/selection/index.ts
+++ b/packages/core/src/selection/index.ts
@@ -1,7 +1,4 @@
-import type {
-    // eslint-disable-next-line import/no-named-default
-    default as ContentBlock,
-} from '../block/base/content';
+import type Content from '../block/base/content';
 import type Format from '../block/base/format';
 import type Parent from '../block/base/parent';
 import type ListItem from '../block/commonMark/listItem';
@@ -134,9 +131,9 @@ class Selection {
 
     public doc: Document = document;
     public anchorPath: (string | number)[] = [];
-    public anchorBlock: ContentBlock | null = null;
+    public anchorBlock: Content | null = null;
     public focusPath: (string | number)[] = [];
-    public focusBlock: ContentBlock | null = null;
+    public focusBlock: Content | null = null;
     public anchor: INodeOffset | null = null;
     public focus: INodeOffset | null = null;
     public selectedImage: {
@@ -228,8 +225,8 @@ class Selection {
         if (!anchorDomNode || !focusDomNode)
             return null;
 
-        const anchorBlock = anchorDomNode[BLOCK_DOM_PROPERTY] as ContentBlock;
-        const focusBlock = focusDomNode[BLOCK_DOM_PROPERTY] as ContentBlock;
+        const anchorBlock = anchorDomNode[BLOCK_DOM_PROPERTY] as Content;
+        const focusBlock = focusDomNode[BLOCK_DOM_PROPERTY] as Content;
         const anchorPath = anchorBlock.path;
         const focusPath = focusBlock.path;