This is a Dropdown nav menu using Bootstrap to create a Responsive Web Design ((RWD) Dropdown Navigation using the <header>, <nav>, <section> and <footer> template/demo using HTML5. The 2nd column is placed in the <aside> element. The code and brief Bootstrap tutorial comes from w3schools.com.
"Bootstrap is the most popular HTML, CSS, and JavaScript framework for developing responsive, mobile-first web sites. Bootstrap is completely free to download and use!"
Change the navigation background image color and design.
Right-click and choose View Source to see code and the internal stylesheet
Also be sure to put the internal styles in a separate external .css file.