Choose the Format button on the Home ribbon. You can auto-resize your rows and columns, specify the size, or reset to default ...

Choosing to show or hide gridlines depends on the context, content, readability, and intended use of your spreadsheet. ...

If you want to collapse, show, hide or unhide the Office Ribbon automatically in Word, Excel, and PowerPoint ... which includes some tabs like Home, Insert, Draw, Design, Layout, References ...