You can make it look however you want by changing the correct CSS settings in your Stylesheet section. For the width of the text, here are the main two CSS properties to modify:
margin-left: calc(50vw - 26.375em);
Assuming you have no UI bar on the left, if you want a particular margin width (for example "5em"), regardless of the display size, you can do this:
margin: 2.5em 5em !important;
(where "5em" is the left and right margin width you want, and "2.5em" is the top and bottom margin height)
You can also right-click on the passage, choose "Inspect" on the pop-up menu, click on the <div> where id="passages" and play around with the CSS until you find something you like, then copy all of the changes you made there to your CSS.
Hope that helps! :-)