f7723559_CSS_HTML_XHTML_Reference_Book__Description_and_notes
[Property/Values] border-top-style, border-right-style, border-bottom-style, border-left-style one of none, dotted, dashed, solid, double, groove, ridge, inset, outset, or inherit [Description and notes] 
for defining just the border's style on only one side of an element initial value: none; not inherited
CSS HTML XHTML Reference Book
Description and notes