How to rotate the background image in the container?

Question

Very well done and answered here – http://www.sitepoint.com/css3-transform-background-image/

#myelement:before {
    content: "";
    position: absolute;
    width: 200%;
    height: 200%;
    top: -50%;
    left: -50%;
    z-index: -1;
    background: url(background.png) 0 0 repeat;
    -webkit-transform: rotate(30deg);
    -moz-transform: rotate(30deg);
    -ms-transform: rotate(30deg);
    -o-transform: rotate(30deg);
    transform: rotate(30deg);
}

Very easy method, you rotate one way, and the contents the other. Requires a square though

#element{
    background : url('someImage.jpg');
}
#element:hover{
    transform: rotate(-30deg);
}
#element:hover >*{
    transform: rotate(30deg);
}

Update 2020, May:

Setting position: absolute and then transform: rotate(45deg) will provide a background:

div {
  height: 200px;
  width: 200px;
  outline: 2px dashed slateBlue;
  overflow: hidden;
}
div img {
  position: absolute;
  transform: rotate(45deg);
  z-index: -1;
  top: 40px;
  left: 40px;
}

<div>
  <img src="https://placekitten.com/120/120" />
  <h1>Hello World!</h1>
</div>

Original Answer:

In my case, the image size is not so large that I cannot have a rotated copy of it. So, the image has been rotated with photoshop. An alternative to photoshop for rotating images is online tool too for rotating images. Once rotated, I'm working with the rotated-image in the background property.

div.with-background {
    background-image: url(/img/rotated-image.png);
    background-size:     contain;
    background-repeat:   no-repeat;
    background-position: top center;
}

Good Luck...

CSS:

.reverse {
  transform: rotate(180deg);
}

.rotate {
  animation-duration: .5s;
  animation-iteration-count: 1;
  animation-name: yoyo;
  animation-timing-function: linear;
}

@keyframes yoyo {
  from { transform: rotate(  0deg); }
  to   { transform: rotate(360deg); }
}

Javascript:

$(buttonElement).click(function () {
  $(".arrow").toggleClass("reverse")

  return false
})

$(buttonElement).hover(function () {
  $(".arrow").addClass("rotate")
}, function() {
  $(".arrow").removeClass("rotate")
})

PS: I've found this somewhere else but don't remember the source

I was looking to do this also. I have a large tile (literally an image of a tile) image which I'd like to rotate by just roughly 15 degrees and have repeated. You can imagine the size of an image which would repeat seamlessly, rendering the 'image editing program' answer useless.

My solution was give the un-rotated (just one copy :) tile image to psuedo :before element - oversize it - repeat it - set the container overflow to hidden - and rotate the generated :before element using css3 transforms. Bosh!