Fix: Optimize table style #3221 (#9703)

### What problem does this PR solve?

Fix: Optimize table style
-Modify the style of the table scrollbar and remove unnecessary
scrollbars
-Adjust the header style of the table, add background color and
hierarchy
-Optimize the style of datasets and file tables
-Add a new background color variable

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

web/src/locales/en.ts

@@ -837,7 +837,7 @@ This auto-tagging feature enhances retrieval by adding another layer of domain-s
     fileManager: {
       name: 'Name',
       uploadDate: 'Upload Date',
-      knowledgeBase: 'Knowledge Base',
+      knowledgeBase: 'Dataset',
       size: 'Size',
       action: 'Action',
       addToKnowledge: 'Link to Knowledge Base',