os x app store menu bar lost
It's been a while I using the latest OS X High Sierra version as I always apply updates as soon as it released. And yesterday I found the menu bar, or say navigation bar, what ever name is that should be on the top of my App Store was lost. Moreover, the layout of App Store page became strange, while links & buttons inside are still functioning. How to deal with this? How to reset my App Store to normal?
MacBook (Retina, 12-inch, Early 2015), macOS High Sierra (10.13.6)