[risk=no][RW-4834]Quick Tour: fix overflow, scaling and layering issues (#3485)
[risk=no][RW-4834]Quick Tour: fix overflow, scaling and layering issues (#3485)

* Correct overflow, scaling and layering issues

* use FlexColumn

* Factor out some styling

* Remove unnecessary spread
all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench