CSS: 100% width or height while keeping aspect ratio?

Question

Currently, with STYLE, I can use width: 100% and auto on the height (or vice versa), but I still can\'t constrain the image into a specific positio

Answer 1

Not to jump into an old issue, but...

#container img {
      max-width:100%;
      height:auto !important;
}

Even though this is not proper as you use the !important override on the height, if you're using a CMS like WordPress that sets the height and width for you, this works well.