LibGuides can be accessed from multiple types of devices, so it's important to double check that the guide looks how you want it to on mobile devices as well. An easy way to do this is to use the inspect option from the right-click menu. Just right-click on the screen, press inspect, and in the top left corner of the inspect screen there will be a symbol that looks like a laptop and a phone (hovering over it will show "Toggle device toolbar.") With this toolbar enabled, you can change the screen dimensions to fit a tablet or phone's dimensions.
Though, this will only show what the page looks like from an editor's view. To see what it would look like from a viewer's point of view, click the eye symbol next to the red publish button. This opens the preview version of the guide in another tab. You can use the same trick shown above to then see what the published guide would look like on a mobile device.
Making the text size larger can help the guide be easier to read. Larger text can help people have a better experience with the guide, and it can help reduce eye strain. The default font size is a little too small for the text to stand out as well. For example: