How to triangle top and bottom border?

Question

As you can see in the image below, I am trying to warp or triangle my div from bottom and top, but I have no idea how to do it. I just tried a couple of times to do it, but

Answer 1

This can be done using CSS triangles on the ::before and ::after pseudo-elements! I've colored them brightly so you can tell what's happening, but it should be somewhat easy to get these to look they way you want.

body {
  background: lightblue;
}

.block {
  background-image: linear-gradient(to right, #314b56, #283b44, #1f2c32, #161e21, #0a0f11);
  border: 1px solid #fff;
  width: 300px;
  height: 150px;
  margin: 30px;
  position: relative;
}

.block::before,
.block::after{
  display: block;
  content: '';
  position: absolute;
  border: 150px solid transparent;
}

.block::before {
  border-top-width: 0;
  border-bottom-width: 25px;
  border-bottom-color: red;
  top: -25px;
}

.block::after {
  border-bottom-width: 0;
  border-top-width: 25px;
  border-top-color: green;
  bottom: -25px;
}

<div class="block"></div>

Answer 2

An idea using transformation and perspective where you will have the border, border-radius also the gradient:

body {
  background: lightblue;
}

.block {
  overflow: hidden;
  width: 300px;
  height: 200px;
  margin: 20px;
  position: relative;
  z-index:0;
}

.block::before,
.block::after {
  content: "";
  position: absolute;
  z-index:-1;
  border: 1px solid #fff;
  top: 0;
  bottom: 0;
  width: 50%;
  background-image: linear-gradient(to right, #314b56, #283b44, #1f2c32, #161e21, #0a0f11);
  background-size: 200% 100%;
}

.block::before {
  left: 0;
  border-right: 0;
  border-radius: 15px 0 0 15px;
  transform-origin: right;
  transform: perspective(100px) rotateY(-5deg);
}

.block::after {
  right: 0;
  border-left: 0;
  border-radius: 0 15px 15px 0;
  transform-origin: left;
  transform: perspective(100px) rotateY(5deg);
  background-position: right;
}

<div class="block"></div>

You can also add the shadow and easily change the gradient:

body {
  background: lightblue;
}

.block {
  overflow: hidden;
  width: 300px;
  height: 200px;
  margin: 20px;
  position: relative;
  z-index:0;
  filter:drop-shadow(0 0 5px #000);
}

.block::before,
.block::after {
  content: "";
  position: absolute;
  z-index:-1;
  border: 1px solid #fff;
  top: 0;
  bottom: 0;
  width: 50%;
  background-image: linear-gradient(35deg, blue, red);
  background-size: 200% 100%;
}

.block::before {
  left: 0;
  border-right: 0;
  border-radius: 15px 0 0 15px;
  transform-origin: right;
  transform: perspective(100px) rotateY(-5deg);
}

.block::after {
  right: 0;
  border-left: 0;
  border-radius: 0 15px 15px 0;
  transform-origin: left;
  transform: perspective(100px) rotateY(5deg);
  background-position: right;
}

<div class="block"></div>

Answer 3

Adjust the measurements to fit your exact shape requirements. This gives something close to what you are looking for.

body{
background:lightblue;;
}
.block{ position: 
relative; width:200px; 
height: 150px;
margin: 20px 0;
background: red;
border-radius: 50% / 10%;
background-image: linear-gradient(to right, #314b56, #283b44, #1f2c32, #161e21, #0a0f11);:
 }


}
.block:before
{ content: '';
position: absolute;
top: 20%; 
bottom: 20%; 
right: -5%; 
left: -5%; 
background: inherit;
border-radius: 5% / 50%;
}

<div class="block"></div>

Answer 4

You can do it with clip-path. There is a really simple tool that could help you: https://bennettfeely.com/clippy/.

I've made an example for you with your content:

body {
  background: lightblue;
}

.block {
  background-image: linear-gradient(to right, #314b56, #283b44, #1f2c32, #161e21, #0a0f11);
  border: 1px solid #fff;
  width: 300px;
  height: 150px;
  margin: 30px;
  -webkit-clip-path: polygon(100% 80%, 50% 100%, 0 80%, 0 20%, 51% 0, 100% 20%);
  clip-path: polygon(100% 80%, 50% 100%, 0 80%, 0 20%, 51% 0, 100% 20%);
}

<div class="block"></div>