CSS margin-left transition not working

Question

I'm trying to do a transition from the center to left and reduce the height of an image. The height transition is working fine, but the margin just teleports to the left instead of animating.

this is my code:

#logo_img {
    height: 55px;
    width: 55px;
    background-color: red;
    margin-left: auto;
    margin-right: auto;
    display: block;
    transition: all 1s ease-in-out;
}

#logo_img.tiny {
    height:45px;
    margin-left: 0;
}

JS:

$('#logo_img').addClass('tiny');

working example: http://jsfiddle.net/v0w6s3ms/1/

any help?

Answer 1

You can't animate auto property instead try something like this

$(function() {
  setTimeout(function() {
    $('#logo_img').addClass('tiny');
  }, 1000);
});

#logo_img {
  height: 55px;
  width: 55px;
  background-color: red;
  margin-left: calc(50% - 55px);
  margin-right: auto;
  display: block;
  transition: all 1s ease-in-out;
}
#logo_img.tiny {
  height: 45px;
  margin-left: 0;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<section id="logo_img"></section>

Answer 2

You want to transition from "margin-left:auto" to "margin-left:0". Auto is not a defined value, thats why it can't be decreased to zero. Set margin-left: 50% instead "auto".