How do I make a transparent border with CSS?

I have an li styled as follows:

li{
    display:inline-block;
    padding:5px;
    border:1px solid none;
}
li:hover{
    border:1px solid #FC0;
}

When I hover over the li the border appears without making the li's shift around. Is it possible to have a 'border' that's not visible?

You can use "transparent" as a colour. In some versions of IE, that comes up as black, but I've not tested it out since the IE6 days.

http://www.researchkitchen.de/blog/archives/css-bordercolor-transparent.php

Many of you must be landing here to find a solution for opaque border instead of a transparent one. In that case you can use rgba, where a stands for alpha.

.your_class {
    height: 100px;
    width: 100px;
    margin: 100px;
    border: 10px solid rgba(255,255,255,.5);
}

Demo

Here, you can change the opacity of the border from 0-1

---

If you simply want a complete transparent border, the best thing to use is transparent, like border: 1px solid transparent;

You could remove the border and increase the padding:

li {
  display: inline-block;
  padding: 6px;
  border-width: 0px;
}

li:hover {
  border: 1px solid #FC0;
  padding: 5px;
}

<ul>
  <li>Hovering is great</li>
</ul>

hey this is the best solution I ever experienced.. this is CSS3

use following property to your div or anywhere you wanna put border trasparent

e.g.

div_class { 
 border: 10px solid #999;
 background-clip: padding-box; /* Firefox 4+, Opera, for IE9+, Chrome */
}

this will work..

Yep, you can use border: 1px solid transparent

Another solution is to use outline on hover (and set the border to 0) which doesn't affect the document flow:

li{
    display:inline-block;
    padding:5px;
    border:0;
}
li:hover{
    outline:1px solid #FC0;
}

NB. You can only set the outline as a sharthand property, not for individual sides. It's only meant to be used for debugging but it works nicely.

Since you said in a comment that the more options you have, the better, here's another one.

In CSS3, there are two different so-called "box models". One adds the border and padding to the width of a block element, while the other does not. You can use the latter by specifying

-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
-ms-box-sizing: border-box;
box-sizing: border-box;

Then, in modern browsers, the element will always have the same width. I.e., if you apply a border to it on hover, the width of the border will not add to the overall width of the element; the border will be added "inside" the element, so to speak. However, if I remember correctly, you must specify the width explicitly for this to work. Which is probably not an option for you in this particular case, but you can keep it in mind for future situations.

This blog entry has a way to emulate border-color: transparent in IE6. The below example includes the "hasLayout" fix that is brought up in the blog entry comments:

/* transparent border */
.testDiv {
    width: 200px;
    height: 200px;
    border: solid 10px transparent;
}
/* IE6 fix */
*html .testDiv {
    zoom: 1;
    border-color: #FEFEFE;
    filter: chroma(color=#FEFEFE);
}

Make sure that the border-color used in the IE6 fix is not used anywhere in the .testDiv element. I changed the example from pink to #FEFEFE because that seems even less likely to be used.

Use transparent property

border-color : transparent;

The easiest solution to this is to use rgba as the color: border-color: rgba(0,0,0,0); That is fully transparent border color.