CSS- how to give an object with scooped corners a border colour?

Question

I created the following object with scooped borders ... http://jsfiddle.net/zjw3pg2e/

I want a way using pure CSS to give the object a black border. All my attempts at doing so have thus far failed.

HTML:

<div class="box"></div>

CSS:

 .box {
    position:relative;
    height:200px;
    width:200px;
    overflow:hidden;
    /*border: solid 2px black;*/ 
}
.box:before{
    content:'';
    position:absolute;
    /*border: solid 2px black;*/
    left:0;
    margin:-20px;
    height:40px;
    width:40px;
    border-radius:100%;
    background:white;
    box-shadow:200px 0 0 white,
    0 200px 0 white,
    200px 200px 0 white,
    0 0 0 500px blue;   
}

I tried setting the border for .box and .box:before as border: solid black 2px;, but this doesn't do what I am trying to achieve. I need the border to fit the shape of the object perfectly.

I suspect there's a way to do it by altering the box-shadow, but I can't figure it out. Any help is appreciated.

possible duplicate of [Is there any way to invert a rounded corner in CSS?](http://stackoverflow.com/questions/4012085/is-there-any-way-to-invert-a-rounded-corner-in-css) — TylerH, Dec 31 '14 at 21:56
@TylerH don't think so... I know how to invert a rounded corner, and I'm not asking how to invert the borders, I just want to give my shape a black border. The question http://stackoverflow.com/questions/4012085/is-there-any-way-to-invert-a-rounded-corner-in-css doesn't answer my question... — buydadip, Dec 31 '14 at 21:57

score 3 · Accepted Answer · answered Dec 31 '14 at 22:03

I did it with pure css in this example using 4 extra divs:

If youre worried about overflow you can just wrap it in an extra div.

JS FIDDLE

css:

.corner {
background:#fff;
height:20px;
width:20px;    
position:absolute;
}
#sw {
left: -2px;
bottom: -2px;
border-radius: 0px 20px 0px 0px;
border-top: 2px solid #000;
border-right: 2px solid #000;
}
#se {
right: -2px;
bottom: -2px;
border-radius: 20px 0px 0px 0px;
border-top: 2px solid #000;
border-left: 2px solid #000;
}
#nw {
left: -2px;
top: -2px;
border-radius: 0px 0px 20px 0px;
border-bottom: 2px solid #000;
border-right: 2px solid #000;
}
#ne {
right: -2px;
top: -2px;
border-radius: 0px 0px 0px 20px;
border-bottom: 2px solid #000;
border-left: 2px solid #000;
}

.box {
    position:relative;
    height:200px;
    width:200px;
    border: solid 2px black;
    background:blue;
    border-radius: 5px -5px 5px 5px;
}

html:

<div class="box">
    <div id="ne"  class="corner"></div>
    <div id="nw" class="corner"></div>
    <div id="se" class="corner"></div>
    <div id="sw" class="corner"></div>
</div>

TheIronDeveloper · Answer 2 · 2014-12-31T22:26:15.540

So the solution I came up with... uses 3 divs (an outer-box, box, and inner-box).

The box:before/:after and box-inner:before/:after are the semi-circles. around the sides, that I gave a white background with a black border.

JS Fiddle

.box-wrapper{
    position:relative;
    height:202px;
    width:202px;
    overflow:hidden;
}
.box {
    
    position: absolute;
    height:200px;
    width:200px;
    background: blue;
    border: 1px solid #000;

}

.box:before,
.box:after,
.box-inner:before,
.box-inner:after {
    background: #fff;
    content: ' ';
    display: block;
    height: 3em;
    width: 3em;
    border-radius: 50%;
    border: solid 1px black;
    position: absolute;
}
.box:before {
    top: -1.5em;
    left: -1.5em;
}
.box:after {
    top: -1.5em;
    right: -1.5em;
}
.box-inner:before {
    bottom: -1.5em;
    left: -1.5em;
}
.box-inner:after {
    bottom: -1.5em;
    right: -1.5em;
}

<div class="box-wrapper">
    <div class="box">
        <div class="box-inner"></div>
    </div>
</div>

Normally you can apply a box-shadow: 0 0 1px #000;, which lets you give a border-like effect on top of borders, however the circles make the relative .box div will always sit on top of its :before/:after (making the box-shadow solution unobtainable).

CSS- how to give an object with scooped corners a border colour?

2 Answers2