marking a column on a gantt chart...

Hi @Dave K

The only formatting you can apply vertically in a Gantt view in Smartsheet is if you set a Day/Date as a Holiday in your Project Settings. That day will appear light pink and it will not be counted in the duration of the task:

However if you want to highlight a day for visibility, this currently isn't possible in Smartsheet. You could highlight a row all the way through the chart, but not a day. Please submit your feature request through this form, here!

Thanks,

Genevieve