如何使顶部和底部边框成三角形？

Question

如下图所示，我正在尝试使div从底部和顶部弯曲或成三角形，但我不知道该怎么做。我只是尝试了几次，但是无法达到目的。那么如何在psuedo之后使用它呢？伪装无关紧要，但我想知道怎么做？

这是我的代码：

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;
}

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

Answer 1

使用变换和透视图的想法，您将获得边界，边界半径和渐变：

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>

您还可以添加阴影并轻松更改渐变：

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 2

您可以使用clip-path进行操作。有一个非常简单的工具可以帮助您：https://bennettfeely.com/clippy/。

我已经为您举例说明了您的内容

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>

Answer 3

这可以通过在::before和::after伪元素上使用CSS三角形来完成！我给它们涂上了鲜艳的颜色，这样您就可以知道发生了什么，但是让它们看起来像您想要的那样应该很容易。

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 4

调整尺寸以适合您的确切形状要求。这样可以提供与您想要的东西接近的东西。

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>