I am trying to make a <ul>
slide down using CSS transitions.
The <ul>
starts off at height: 0;
. On hover, the height is set to height:auto;
. However, this is causing it to simply appear, not transition,
If I do it from height: 40px;
to height: auto;
, then it will slide up to height: 0;
, and then suddenly jump to the correct height.
How else could I do this without using JavaScript?
#child0 { height: 0; overflow: hidden; background-color: #dedede; -moz-transition: height 1s ease; -webkit-transition: height 1s ease; -o-transition: height 1s ease; transition: height 1s ease; } #parent0:hover #child0 { height: auto; } #child40 { height: 40px; overflow: hidden; background-color: #dedede; -moz-transition: height 1s ease; -webkit-transition: height 1s ease; -o-transition: height 1s ease; transition: height 1s ease; } #parent40:hover #child40 { height: auto; } h1 { font-weight: bold; }
The only difference between the two snippets of CSS is one has height: 0, the other height: 40. <hr> <div id="parent0"> <h1>Hover me (height: 0)</h1> <div id="child0">Some content <br>Some content <br>Some content <br>Some content <br>Some content <br>Some content <br> </div> </div> <hr> <div id="parent40"> <h1>Hover me (height: 40)</h1> <div id="child40">Some content <br>Some content <br>Some content <br>Some content <br>Some content <br>Some content <br> </div> </div>
For animate the "height" of element with CSS Transitions you need use "max-height". If use the "height: auto", the effect not works. Is necessary some value for the CSS create a CSS animate, and you can use "max-height" with a great value for emulate this effect.
We can't transition height , but we can transition max-height , since it has an explicit value. At any given moment, the actual height of the element will be the minimum of the height and the max-height .
The transition-timing-function property can have the following values: ease - specifies a transition effect with a slow start, then fast, then end slowly (this is default) linear - specifies a transition effect with the same speed from start to end. ease-in - specifies a transition effect with a slow start.
CSS transitions provide a way to control animation speed when changing CSS properties. Instead of having property changes take effect immediately, you can cause the changes in a property to take place over a period of time.
Use max-height
in the transition and not height
. And set a value on max-height
to something bigger than your box will ever get.
See JSFiddle demo provided by Chris Jordan in another answer here.
#menu #list { max-height: 0; transition: max-height 0.15s ease-out; overflow: hidden; background: #d5d5d5; } #menu:hover #list { max-height: 500px; transition: max-height 0.25s ease-in; }
<div id="menu"> <a>hover me</a> <ul id="list"> <!-- Create a bunch, or not a bunch, of li's to see the timing. --> <li>item</li> <li>item</li> <li>item</li> <li>item</li> <li>item</li> </ul> </div>
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