How to achieve chamfered CSS Border Corners rather than rounded corners?

Question

With the CSS border-radius property I can have a curvy, rounded border corner at the end.

.boxLeft{
             


        

Answer 1

++ Includes Westworld Style UI in CSS ++

I've updated AlphaMale's awesome answer to hack chamfered borders as originally requested. It basically uses one chamfered div with a slightly smaller on inside it. The outer div's background colour becomes the border colour when the rest of it is covered up by the inner div with matching chamfers.

Tested in Edge, Chrome and Firefox.

I found this page while looking to duplicate something like the Westworld User Interface which has unequal chamfered corners. See the JS fiddle for how I've cobbled this together along with a colour scheme and example box from the Westworld speech chaining scene.

Code on JSFiddle (CSS below): http://jsfiddle.net/S2nqK/345/

Westworld UI pic at: https://qph.ec.quoracdn.net/main-qimg-44c9f03b2abfe9f3833763eece1b0cc4?convert_to_webp=true

body {background-color: #353535;
font-family: 'Open Sans';}
.div-outer {

 /* Chrome / Safari */
    background:
        -webkit-linear-gradient(45deg,  transparent 0px, #6ea1a1 0px), /* bottom left */
        -webkit-linear-gradient(135deg, transparent 14px, #6ea1a1 14px), /* bottom right */
        -webkit-linear-gradient(225deg, transparent 0px, #6ea1a1 0px), /* top right */
        -webkit-linear-gradient(315deg, transparent 5px, #6ea1a1 5px); /* top left */

    /* Firefox */
        background:
        -moz-linear-gradient(45deg,  transparent 0px, #6ea1a1 0px), /* bottom left */
        -moz-linear-gradient(135deg, transparent 14px, #6ea1a1 14px), /* bottom right */
        -moz-linear-gradient(225deg, transparent 0px, #6ea1a1 0px), /* top right */
        -moz-linear-gradient(315deg, transparent 5px, #6ea1a1 5px); /* top left */

     /* Opera */
        background:
        -o-linear-gradient(45deg,  transparent 0px, #6ea1a1 0px), /* bottom left */
        -o-linear-gradient(135deg, transparent 14px, #6ea1a1 14px), /* bottom right */
        -o-linear-gradient(225deg, transparent 0px, #6ea1a1 0px), /* top right */
        -o-linear-gradient(315deg, transparent 5px, #6ea1a1 5px); /* top left */


   padding: 2px;
   color: #fff;

}

.div-inner {


    background:
        -webkit-linear-gradient(45deg,  transparent 0px, #000 0px),
        -webkit-linear-gradient(135deg, transparent 14px, #000 14px),
        -webkit-linear-gradient(225deg, transparent 0px, #000 0px),
        -webkit-linear-gradient(315deg, transparent 5px, #000 5px);

         background:
        -moz-linear-gradient(45deg,  transparent 0px, #000 0px),
        -moz-linear-gradient(135deg, transparent 14px, #000 14px),
        -moz-linear-gradient(225deg, transparent 0px, #000 0px),
        -moz-linear-gradient(315deg, transparent 5px, #000 5px);

         background:
        -o-linear-gradient(45deg,  transparent 0px, #000 0px),
        -o-linear-gradient(135deg, transparent 14px, #000 14px),
       -o-linear-gradient(225deg, transparent 0px, #000 0px),
        -o-linear-gradient(315deg, transparent 5px, #000 5px);


   padding: 10px;

   height: 92px;
   text-align: center;
}


.div-outer, .div-inner {
    background-position: bottom left, bottom right, top right, top left;
    -moz-background-size: 50% 50%;
    -webkit-background-size: 50% 50%;
    background-size: 50% 50%;
    background-repeat: no-repeat;
}

.contain {
   width: 180px;
}
.title {background-color: #76ffff; 
  padding: 6px;
  color: #000;
  border-radius: 2px;
  font-weight: bold;
 text-align-last: justify;
 text-align: justify;
  }
.font-large {font-size: 34pt;}
.font-tiny {font-size: 10pt;}
.cyan {color: #76ffff;}
/* Ignore the CSS from this point, it's just to make the demo more presentable */

.arrow-right {
  width: 0; 
  height: 0; 
  border-top: 8px solid transparent;
  border-bottom: 8px solid transparent;
  border-left: 8px solid #fff;
  display: inline-block;
  vertical-align: middle;
}


p:first-of-type { margin-top: 0 }
p:last-of-type { margin-bottom: 0}