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Viewing PDFs and viewing preferences
https://helpx.adobe.com/acrobat/using/viewing-pdfs-viewing-preferences.html
View PDFs in Read mode
When you’re reading a document, you can hide all the toolbars and task panes to maximize the viewing area on your screen.
The basic reading controls, such as page navigation and zoom, appear in a semi-transparent floating toolbar near the bottom of the window.
• To open Read mode, choose View > Read Mode, or click the Read Mode button in the upper-right corner of the toolbar.
• To restore the work area to its previous view, choose View > Read Mode again. You can also click the close button in the floating toolbar.
Note:
Read mode is the default viewing mode when you open a PDF in a web browser.
Read mode's semi-transparent floating toolbar presents at the bottom center of the PDF.