Disable horizontal scrolling in right outlet
Disable horizontal scrolling in right outlet

Closes #4131

- Adds `overflow-x: hidden;` to `.right-outlet`

JohnONolan/Ghost-Admin,acburdine/Ghost-Admin,acburdine/Ghost-Admin,dbalders/Ghost-Admin,kevinansfield/Ghost-Admin,kevinansfield/Ghost-Admin,JohnONolan/Ghost-Admin,dbalders/Ghost-Admin,TryGhost/Ghost-Admin,airycanon/Ghost-Admin,airycanon/Ghost-Admin,TryGhost/Ghost-Admin