CSS to create curved corner between two elements?

Question

My UI has an unordered list on the left. When a list item is selected, a div appears on the right of it. I\'d like to have a curved outer corner

Answer 1

Well, as it turns out, I managed to solve the problem myself. I hacked together a demo -- check it out.

Essentially, several additional DOM elements are required and a fair amount of CSS. And as mentioned in the link provided by @Steve, a solid background is required. I don't believe there is any way to do this over a gradient background or other pattern.

I ended up with HTML like this:

ul.selectable {
  padding-top: 1em;
  padding-bottom: 1em;
  width: 50%;
  float: left;
}
ul.selectable li {
  margin: 0 3em 0 4em;
  border-radius: 8px;
  -webkit-border-radius: 8px;
  -khtml-border-radius: 8px;
  -moz-border-radius: 8px;
}
ul.selectable li.active {
  margin-right: 0;
}
ul.selectable li.active dl {
  background-color: #4f9ddf;
}
ul.selectable li dt {
  background-color: #dfd24f;
  padding: 1em;
  margin-left: -2em;
  margin-right: -2em;
  -webkit-border-radius: 8px;
  -khtml-border-radius: 8px;
  -moz-border-radius: 8px;
  border-radius: 8px;
}
ul.selectable li dd {
  padding: 0.25em;
  background-color: #fff;
}
ul.selectable li.active dt {
  background-color: #4f9ddf;
  margin-right: 0;
  -webkit-border-top-right-radius: 0;
  -webkit-border-bottom-right-radius: 0;
  -khtml-border-top-right-radius: 0;
  -khtml-border-bottom-right-radius: 0;
  -moz-border-radius-topright: 0;
  -moz-border-radius-bottomright: 0;
  border-top-right-radius: 0;
  border-bottom-right-radius: 0;
}
ul.selectable li.active dd.top {
  -webkit-border-bottom-right-radius: 8px;
  -khtml-border-bottom-right-radius: 8px;
  -moz-border-radius-bottomright: 8px;
  border-bottom-right-radius: 8px;
}
ul.selectable li.active dd.bot {
  -webkit-border-top-right-radius: 8px;
  -khtml-border-top-right-radius: 8px;
  -moz-border-radius-topright: 8px;
  border-top-right-radius: 8px;
}
div.right {
  float: left;
  padding-top: 3em;
  width: 50%;
}
div.content {
  height: 15em;
  width: 80%;
  background-color: #4f9ddf;
  padding: 1em;
  -webkit-border-radius: 8px;
  -khtml-border-radius: 8px;
  -moz-border-radius: 8px;
  border-radius: 8px;
}

  

    

      

      
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I haven't optimized any of the CSS as I just hacked it together. But perhaps it will help someone else. I've only tested this in Google Chrome on Mac OSX.