Each new page in Webflow starts with the <body>. This contains all the contents such as text, hyperlinks, images, tables, lists.
By default the <body> has a margin of 8px in most browsers. However, in Webflow, this is removed. There is no default margin. Unless you want your elements right against the edge of the screen, you need to set your own margin in Webflow > Style (S) > Spacing > Margin
The CSS removing the margin in <body> looks like this:
Note that the standard Webflow container I use on this page DOES NOT have the 940px width on smaller devices (tablets and mobile). In this case, all the text is next to the edge of the screen.