The border property

p
{ 
border: thin dotted #00FF00
}

span
{ 
border: solid #0000FF
} 

Notes in IE 4.0:

• This property does not work on checkboxes and radiobuttons
• This property on list items moves the list item marker

Note in IE 4.0+:

• This property does not work with inline elements

Note in IE 5.5 Beta 1:

• This property works with inline elements

Notes in Netscape 4.0:

• Border properties turn inline elements into block elements
• Border properties do not work (properly) with tables, table cells, form fields, hyperlinks, images, lists, and list items
• Default value for "border-style" is "solid", not "none" as it is written in the specification
• Default value for "border-width" is "0", not "medium" as it is written in the specification