Question

I just found out that floating an element will also make it a block, therefore specifying a float property and display:block is redundant.

(What would happen if you tried to specify display:inline and float:left? )

Are there any other examples of redundant combinations to watch out for? block & width ? etc,

Is there a tool that can check for such things?

Answer 1

I just found out that floating an
element will also make it a block,
therefore specifying a float property
and display:block is redundant.

Yes, display: block is redundant if you’ve specified float: left (or right).

(What would happen if you tried to
specify display:inline and float:left?
)

display: inline will not make any difference, because setting float: left forces display: block “no matter what”:

http://www.w3.org/TR/CSS2/visuren.html#dis-pos-flo

Otherwise, if ‘float’ has a value
other than ‘none’, the box is floated
and ‘display’ is set according to the
table below.

To summarize said table: float = display: block.

However, your specific example of float: left; display: inline is useful in one way – it fixes an IE6 bug.

Are there any other examples of
redundant combinations to watch out
for? block & width ? etc,

Some examples:

• If you set position: absolute, then float: none is forced.
• The top, right, bottom, left properties will not have any effect unless position has been set to a value other than the default of static.

Is there a tool that can check for
such things?

I don’t think so. It’s not something that is ever needed, so I can’t see why anybody would have written such a tool.