The top-right toolbar: Single View, Guides, Grid, and Run Layout
At the top right of the previewer, you should see three rows of buttons. At the top are your standard page navigation buttons, to take you back to the Dashboard, to your Settings options, and the book info editor.
Just below that, you have three buttons:
Single View: This doesn’t do much right now, but soon it will allow you toggle between viewing your pages as spreads or as single pages.
Guides: This button toggles your page guides on and off. This guides highlight the different margin areas and the page content area, so that you can see how everything lines up.
Grid: This toggles on and off your baseline grid, which is determined by your line-height setting in the General Page Design menu. When you turn this on, you’ll see a grid of horizontal lines on all your pages, so that you can adjust your text margins and padding as needed to ensure it all lines up with the baseline grid.
Below your view options, you’ll see the current page count for your book, and the Run Layout button. The Run Layout button will become your best “frenemy” as you use the app, and is how you reflow your content through your pages after you update the design.
Reflowing your content can take up to a couple of minutes, especially for longer books, so instead of forcing you to wait a couple of minutes every time you make one change, we’re putting you in control over when to reflow your pages. You can make a bunch of design adjustments all at once, and most of the changes will automatically appear in the previewer window (an example of things that won’t appear until after you click Run Layout are changes to margins and padding), but your text won’t reflow, which means that pages might run short or overflow as you make adjustments. Once you’ve made a handful of changes and really need to see the new pages (and page count), click Run Layout to trigger the page reflow.