How to make Background div inner curved using HTML

问题:

I want my section background look like as shown in the image at the end, how can i do that using css?

.bg{
  width: 400px;
  height: 200px;
  padding: 20px;
  text-align: center;
  border: 1px solid #000;
  background: red;
  color: #fff;
  display: flex;
}
.bg p{
  text-align: center;
  margin: auto;
  font-size: 36px;
}

<div class="bg">
  <p>Section Content</p>
</div>

回答1:

Use linear-gradient like this without the need of extra elements or pseudo-element:

.bg{
  width: 400px;
  height: 200px;
  padding: 20px;
  text-align: center;
  background:
  linear-gradient(to bottom left, red 50%,#fff 51%) 0 100%/50% 50px no-repeat,
  linear-gradient(to bottom right, red 50%,#fff 51%) 100% 100%/50% 50px no-repeat,
  linear-gradient(to bottom right, #fff 49%,red 50%) 100% 0/50% 50px no-repeat,
  linear-gradient(to bottom left, #fff 49%,red 50%) 0 0/50% 50px no-repeat,
  red;
  color: #fff;
  display: flex;
}
.bg p{
  text-align: center;
  margin: auto;
  font-size: 36px;
}

<div class="bg">
  <p>Section Content</p>
</div>

But in case you need border around I would then consider pseudo-elements like this:

.bg{
  width: 400px;
  height: 200px;
  padding: 20px;
  text-align: center;
  position:relative;
  color: #fff;
  display: flex;
  z-index:0;
}
.bg:before,
.bg:after{
  content:"";
  position:absolute;
  top:0;
  bottom:0;
  background:red;
  border:2px solid #000;
  z-index:-1;
}
.bg:before {
  right:50%;
  left:0;
  transform:skewY(15deg);
  transform-origin:top left;
  border-right:none;
}
.bg:after {
  left:50%;
  right:0;
  transform:skewY(-15deg);
  transform-origin:top right;
  border-left:none;
}
.bg p{
  text-align: center;
  margin: auto;
  font-size: 36px;
}

<div class="bg">
  <p>Section Content</p>
</div>

回答2:

You can use clip-path to do such things and create them using this tool.

.bg {
  width: 400px;
  height: 200px;
  padding: 20px;
  text-align: center;
  border: 1px solid #000;
  background: red;
  color: #fff;
  display: flex;
  -webkit-clip-path: polygon(100% 0, 100% 80%, 50% 100%, 0 80%, 0 0, 50% 20%);
  clip-path: polygon(100% 0, 100% 80%, 50% 100%, 0 80%, 0 0, 50% 20%);
}

.bg p {
  text-align: center;
  margin: auto;
  font-size: 36px;
}

<div class="bg">
  <p>Section Content</p>
</div>

回答3:

You can do as follows to get shape you needed.

.left {
  -webkit-box-sizing: content-box;
  -moz-box-sizing: content-box;
  box-sizing: content-box;
  width: 150px;
  height: 200px;
  border: none;
  color: rgba(0,0,0,1);
  -o-text-overflow: clip;
  text-overflow: clip;
  background: #1abc9c;
  -webkit-transform:    skewY(15deg);
  transform:    skewY(15deg);
  float: left;
  margin-top: 20px;
}

.right {
  -webkit-box-sizing: content-box;
  -moz-box-sizing: content-box;
  box-sizing: content-box;
  width: 150px;
  height: 200px;
  border: none;
  color: rgba(0,0,0,1);
  -o-text-overflow: clip;
  text-overflow: clip;
  background: #1abc9c;
  -webkit-transform:    skewY(-15deg);
  transform:    skewY(-15deg);
  float: left;
  margin-top: 20px;
}

<div class="left">Hello</div>	
<div class="right">World</div>