How to center an image horizontally and align it t

问题:

How can I center an image horizontally and aligned to the bottom of the container at the same time?

I have been able to center the image horizontally by its self. I have also been able to align the bottom of the container by its self. But I have not been able to do both at the same time.

Here is what I have:

.image_block {
    width: 175px;
    height: 175px;
    position: relative;
    margin: 0 auto;
}
.image_block a img {
position: absolute;
bottom: 0;
}

<div class="image_block">
    <a href="..."><img src="..." border="0"></a>
</div>

That code aligns the image to the bottom of the div. What do I need to add/change to make it also center the image horizontally inside the div? The image size is not known before hand but it will be 175x175 or less.

回答1:

.image_block    {
    width: 175px;
    height: 175px;
    position: relative;
}

.image_block a  {
    width: 100%;
    text-align: center;
    position: absolute;
    bottom: 0px;
}

.image_block img    {
/*  nothing specific  */
}

explanation: an element positioned absolutely will be relative to the closest parent which has a non-static positioning. i'm assuming you're happy with how your .image_block displays, so we can leave the relative positioning there.

as such, the <a> element will be positioned relative to the .image_block, which will give us the bottom alignment. then, we text-align: center the <a> element, and give it a 100% width so that it is the size of .image_block.

the <img> within <a> will then center appropriately.

回答2:

This also works (taken a hint from this question)

.image_block {
  height: 175px;
  width:175px;
  position:relative;
}
.image_block a img{
 margin:auto; /* Required */
 position:absolute; /* Required */
 bottom:0; /* Aligns at the bottom */
 left:0;right:0; /* Aligns horizontal center */
 max-height:100%; /* images bigger than 175 px  */
 max-width:100%;  /* will be shrinked to size */ 
}

回答3:

This is tricky; the reason it's failing is that you can't position via margin or text-align while absolutely positioned.

If the image is alone in the div, then I recommend something like this:

.image_block {
    width: 175px;
    height: 175px;
    line-height: 175px;
    text-align: center;
    vertical-align: bottom;
}

You may need to stick the vertical-align call on the image instead; not really sure without testing it. Using vertical-align and line-height is going to treat you a lot better, though, than trying to mess around with absolute positioning.

回答4:

wouldn't

margin-left:auto;
margin-right:auto;

added to the .image_block a img do the trick?
Note that that won't work in IE6 (maybe 7 not sure)
there you will have to do on .image_block the container Div

text-align:center;

position:relative; could be a problem too.

回答5:

Remove the position: relative; line. I'm not sure why exactly but it fixes it for me.

回答6:

have you tried:

.image_block{
text-align: center;
vertical-align: bottom;
}

回答7:

#header2
{
   display: table-cell;
   vertical-align: bottom;
   background-color:Red;
}


<div style="text-align:center; height:300px; width:50%;" id="header2">
<div class="right" id="header-content2">
  <p>this is a test</p>
</div>
</div>