Target-a-browser 1.2

Attribute (to be used in this order)	Moz/KHTML	IE5/Mac	IE5/Win	IE6/Win	OP5	OP6	OP7
`p { color: blue; }`	blue	blue	blue	blue	blue	blue	blue
`@media not foo { html p { color: green; } } ¹`	blue	blue	blue	blue	blue	blue	green
`p { color: purple; }`	purple	purple	purple	purple	purple	blue	green
`* html p { color: maroon; }`	purple	maroon	maroon	maroon	purple	blue	green
`* html p { co\lor: red; }`	purple	red	maroon	red	purple	blue	green
`html > body p { color: orange; } ²`	orange	orange	maroon	red	purple	blue	green
`* html > body p { color: yellow; }`	orange	yellow	maroon	red	purple	blue	green

→ If this works, you're running Opera 7 and this text is green

→ If this works, you're running Opera 6 and this text is blue

→ If this works, you're running Opera 5 and this text is purple

→ If this works, you're running IE 6 and this text is red

→ If this works, you're running IE 5 and this text is maroon

→ If this works, you're running IE 5/Mac and this text is yellow

→ If this works, you're running Mozilla, Firebird, Netscape 6+, Camino, Safari or Konqueror and this text is orange

¹ Below this, all rules will be ignored by Opera 6+.

² Note the spaces surrounding the child selector (>) making it "Opera-unfriendly".

Please report typos or corrections, or just send a comment.
Many kudos to helpful members of css-discuss, you know who you are.