css transition max-height back to 0 not working

问题

I have a simple div which has height and max-height set to 10px. When I hover over it, it should expand to the full height of div and when I leave it should shrink back to 10px.

But the when I unhover, the code below won't transit smoothly back to 0.

HTML

<div class="animate">
   Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory  ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.10.32.
</div>

CSS

.animate{
  font-size:20px;
  height : 10px;
  max-height:10px;
  width: 100px;
  overflow:hidden;
  -webkit-transition: all 0.5s ease-in-out;
  -moz-transition: all 0.5s ease-in-out;
  -ms-transition: all 0.5s ease-in-out;
  -o-transition: all 0.5s ease-in-out;
  transition: all 0.5s ease-in-out;
}
.animate:hover{
  height:auto;
  max-height:1000px;
}

https://jsfiddle.net/3hfxg6he/2/

回答1:

Remove height:10px; from your code. it ll makes height 10px in high priority and makes overflow-hidden. thats why the animation is not working. for more details about max-height property follow this link

.animate{
  font-size:20px;
  max-height:10px;
  width: 100px;
  overflow:hidden;
  -webkit-transition: all 0.5s ease-in-out;
  -moz-transition: all 0.5s ease-in-out;
  -ms-transition: all 0.5s ease-in-out;
  -o-transition: all 0.5s ease-in-out;
  transition: all 0.5s ease-in-out;
}
.animate:hover{
  height:auto;
  max-height:1000px;
}

<div class="animate">
Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory  ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.10.32.
</div>

来源：https://stackoverflow.com/questions/40850869/css-transition-max-height-back-to-0-not-working

标签

css

css-transitions