Question

Is it possible to get rid of the “triangle” shape in the border corners? (when using different color borders)

See this example:

http://jsfiddle.net/GLsqV/

Any workaround? Basically I just want the top and bottom border to continue, and not have a mix of all of them.

 .borders {  
   width:500px;
   height:500px;
   background:#efefef;
   border:10px solid black;
   border-top:10px solid red;
   border-bottom:10px solid green;
 }​

Answer 1

One option using generated content:

.borders {
    width:500px;
    height:500px;
    position: relative;
    background:#efefef;
    border-top:10px solid red;
    border-bottom:10px solid green;
}

.borders::before,
.borders::after {
    content: '';
    position: absolute;
    width: 10px;
    top: 0;
    bottom: 0;
    background-color: #000;
}

.borders::before {
    left: 0;
}

.borders::after {
    right: 0;
}

JS Fiddle demo.

Or with nested HTML (if you really must):

<div class="borders">
    <div class="innerBorder left"></div>
    <div class="innerBorder right"></div>
</div>​

.borders {
    width:500px;
    height:500px;
    position: relative;
    background:#efefef;
    border-top:10px solid red;
    border-bottom:10px solid green;
}

.borders .innerBorder{
    content: '';
    position: absolute;
    width: 10px;
    top: 0;
    bottom: 0;
    background-color: #000;
}

.borders .left {
    left: 0;
}

.borders .right {
    right: 0;
}

JS Fiddle demo.

And a single-nested-element solution in which the left, and right, border-color is the background-color of the wrapping element, and the width controlled by the margin of the descendant:

<div class="borders">
    <div class="inner"></div>
</div>​

CSS:

.borders {
    width:500px;
    height:500px;
    background-color: #000;
    border-top:10px solid red;
    border-bottom:10px solid green;
}

.borders .inner {
    background-color: #efefef;
    height: 100%;
    margin: 0 10px;
}

JS Fiddle demo.​