任何帮助都是太棒了， a href =https://developer.mozilla.org/en-US/docs/CSS/transform-origin =noreferrer> transform-origin - 在这种情况下，图像旋转的点。

  #image {
 -webkit- transform：rotate（90deg）; 
 -webkit-transform-origin：0 0; //最初50％50％
 margin-left：100％; 
} 
 

90deg fiddle / 270deg fiddle

更新：

是因为我们不能真正修改 transform-origin ，因为它的位置是相对于尚未变换的元素，我们不能设置 margin-top：100％，因为边距值（即使是垂直的）计算为总是相对于包含块的宽度的百分比。以下代码应该工作：

  #image {
 -webkit-transform：rotate（-90deg）; 
 -webkit-transform-origin：0 0; 
 position：relative; 
 top：100％; 
} 
 

Using CSS3, HTML (and javascript/jquery if needed), I need to rotate an image 90/270 degrees and have it position to fill its parent div/container. Sounds simple, but when images are rotated, there positioning changes and I can't figure out how or why.

Here is a jsFiddle to explain - http://jsfiddle.net/UPGkU/2/ - I just want the blue logo to be position exactly within the red div.

Of course, I could use specific offsets, but if a different image is used, those offsets change, so I really want to find a generic solution.

Any help would be fantastic, thanks!

You need to set a transform-origin - in this scenario, a point around which the image gets rotated.

#image {
  -webkit-transform: rotate(90deg);
  -webkit-transform-origin: 0 0; //initially 50% 50%
  margin-left: 100%;
}

90deg fiddle / 270deg fiddle

Update:

The challenge with the latter is that we can't really modify transform-origin as its position is relative to the not yet transformed element and we can't just set margin-top:100% since margin values (even vertical ones) are calculated as a percentage always relative to the width of the containing block. The following code should work:

#image {
  -webkit-transform: rotate(-90deg);
  -webkit-transform-origin: 0 0;
  position:relative;
  top:100%;
}