Revert "add hover style to scroll bar"

This reverts commit 18b6d663f855fb5f3af637fac8f810a28d0e0000.
Revert "Revert "add hover style to scroll bar""

This reverts commit 96d7eaa9559c80223d066f758e2be25dcacb0408.
Revert "Revert "Revert "add hover style to scroll bar"""

This reverts commit 0037c30dea1bcbc1ec314399eb9ce16987b6398e.
Revert "Revert "Revert "Revert "add hover style to scroll bar""""

This reverts commit 8307cd14095415fee5cb0122624bda970e7bdb5e.
use chrome storage to store and synchronize settings