Fix resizer highlight and scroll bar style

app/src/components/Layout/ContentView.tsx

@@ -12,7 +12,6 @@ export default function ContentView(props: {heightProperty: any, paneDefaults: a
       split="vertical"
       minSize={250}
       defaultSize={500}
-      resizerStyle={{ width: '2px', margin: '0 -10px 0 0px' }}
       allowResize={true}
       style={{ position: 'relative' }}
       pane1Style={{ overflow: 'hidden' }}

app/src/components/Sidebar/CodeDiff.tsx

@@ -5,7 +5,6 @@ import { CodeBlockColors, CodeBlockColorsBraceMonokai } from './CodeBlockColors'
 import { selectTextWithCtrlA } from '../../utils/handleTextSelectWithCtrlA'
 import { Theme, withStyles } from '@material-ui/core'
 import 'prismjs/components/prism-json'
-import 'prismjs/themes/prism-tomorrow.css'
 
 interface Props {
   previous: string