🎨 W3.CSS Border Classes Showcase
w3-border
w3-border-top
w3-border-right
w3-border-bottom
w3-border-left
w3-border-0
w3-border-red
w3-border-blue
w3-border-green
w3-hover-border-yellow (Hover me)
w3-bottombar
w3-topbar
w3-leftbar
w3-rightbar