How to create div box with wings or tabs with css - css

Question

I am trying to create a div that looks like that. See the top and bottom with the little tab. I cannot figure out how to do this, it is a "design" thing. I have tried to use the :before :after CSS to create this but no luck. Any ideas?
Added code below. You can see it comes to a point, any way to have it flat?
.container {
width: 150px;
height: 75px;
background-color: white;
border: 3px solid #000;
color: #fff;
padding: 20px;
position: relative;
margin: 40px;
float: left;
}
.container.tab-top:before {
content: " ";
position: absolute;
right: 0px;
top: -15px;
border-top: none;
border-right: 90px solid transparent;
border-left: 90px solid transparent;
border-bottom: 15px solid black;
}
.container.tab-bottom:after {
content: " ";
position: absolute;
right: 0px;
bottom: -15px;
border-top: 15px solid black;
border-right: 90px solid transparent;
border-left: 90px solid transparent;
border-bottom: none;
}
<div class="container tab-top tab-bottom">
</div>

Answer 1

Don't use borders for this. Create a pseudo element and use border-radius.
.container {
width: 150px;
height: 75px;
background-color: white;
border: 3px solid #000;
color: #fff;
padding: 20px;
position: relative;
margin: 40px;
float: left;
}
.container.tab-top:before {
content: " ";
position: absolute;
width: 60%;
height: 7px;
left: 50%;
transform: translateX(-50%);
background: black;
border-radius:20px 20px 0 0;
top: -7px;
}
.container.tab-bottom:after {
content: " ";
position: absolute;
width: 60%;
height: 7px;
left: 50%;
transform: translateX(-50%);
background: black;
border-radius:0 0 20px 20px;
bottom: -7px;
}
<div class="container tab-top tab-bottom">
</div>

Answer 2

You can approximate it using perspective and rotation:
.container {
width: 200px;
height: 100px;
border: 3px solid #000;
position: relative;
margin: 40px
}
.container.tab-top:before,
.container.tab-bottom:after {
content: " ";
position: absolute;
left:15%;
right:15%;
height:30px;
background:#000;
}
.container.tab-top:before {
bottom:100%;
border-radius:10px 10px 0 0;
transform-origin:bottom;
transform:perspective(100px) rotateX(50deg);
}
.container.tab-bottom:after {
top:100%;
border-radius:0 0 10px 10px;
transform-origin:top;
transform:perspective(100px) rotateX(-50deg);
}
<div class="container tab-top tab-bottom">
</div>

Answer 3

You need to use Trapezoid Shape css like:
#trapezoid {
border-bottom: 100px solid red;
border-left: 25px solid transparent;
border-right: 25px solid transparent;
height: 0;
width: 100px;
}
.box {
display: block;
width: 150px;
height: 200px;
border: 2px solid pink;
position: relative;
}
.box::before {
position: absolute;
content: "";
border-bottom: 10px solid pink;
border-left: 15px solid transparent;
border-right: 15px solid transparent;
height: 0;
width: 100px;
top: -10px;
left: 0;
right: 0;
margin: auto;
}
.box::after {
position: absolute;
content: "";
border-top: 10px solid pink;
border-left: 15px solid transparent;
border-right: 15px solid transparent;
height: 0;
width: 100px;
bottom: -10px;
left: 0;
right: 0;
margin: auto;
}
<div class="box"></div>
I used as before after css of a div.