The width of this navbar can be full width or just covering part of the viewport. If the viewport is less than 600px wide, the navbar will change into a 'hamburger' style menu. In case you add menu items, you may have to change those 600px to some more. Just play it 'by ear' by narrowing the viewport and change the width where the navbar breaks into two lines. See comments in the css file styles.css what exactly to change.
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