CSS Menu Stepdown Issue

Normally when floating objects you can count on them lining up vertically until they break. That is, you could if you weren’t using IE 6. IE 6 appends a line break effect after each floated block element which will cause “stepdown”.

The fix here is to make sure the line-height in the parent element is set to zero (0), or that the elements being floated are inline elements.

If you are familiar with the concepts of “floats”, you know that if you float a page element to the left, that the next page element will move up next to that element on the right, if possible. But have you ever seen your floated elements “stepdown”?

This is a fairly common problem you can run into when creating a horizontal menu. Like most menus, you create an unordered list:

<ul id=”menu“>
<li><a href=”#”>My</a></li>
<li><a href=”#”>Little</a></li>
<li><a href=”#”>Menu</a></li>
</ul>

You want the menu items to be large clickable blocks, so you write CSS like this:

ul#menu li a {
display: block;
width: 130px;
text-align: center;
font-weight: bold;
float: left;
color: white;
font-size: 1.2em;
text-decoration: none;
background: #600;
}

Those blocks are floated the left, so they should all line up in a row, right? Nope, that’s gonna get you some stepdown action. The problem is the list elements wrapping the anchor elements. These are also block-level elements but they are not floated. This confuses things, because block elements naturally have a break after them (like an invisible <br />). That pushes the next one down whatever the current line-height is, which is what causes the stepdown.

Here is the remedy:

ul#menu li {
display: inline; /* Prevents “stepdown” */
}

So the possible solutions for this problem are:

• Setting those list elements as inline will take away those breaks and make sure your menu stays nice, happy, and straight!
• Also, the problem is disappear if make line-height:0 to li elements
• Another option would be to float the li elements instead of the links. This will also give you a little more control over the positioning/spacing of each li.

NB: This post is  simplified version of the post from http://css-tricks.com/prevent-menu-stepdown/?. Please refer the original site for more information.