Header almost done

Edited: _app-QualityOS_styles.css, _app-index.html.
Added: images/... QOS_Logo.png, SmallYellowRoundDownArow.png
Header category dropdown

Edited: _app-QualityOS_styles.css, _app-index.html
Dropdown just needs category names and onClicks to correct categories.
Footer started, in progress

Edited: _app-QualityOS_Styles.css, _app-index.html