Changed CSS indentation from 2 to 4 spaces. Moved .project border-style and border-color from layout to themes.
Converted div#nav to nav tag.
Converted div#header and div#footer to header and footer tags.
Converted div#content to article tag.
Changed div.project-item to section.project.
Fixed copyright notice.
Changed project display to flexbox.
Added link to LinkedIn on contact page.