Can I create this shape with CSS only?

Question

I\'m building a hero section for a webpage that has a particular shape, at the moment I\'m just using an image as an overlay for the actual section background, but I\'m look

Answer 1

Here is an idea with one element and radial-gradient to approximate it

.box {
  width: 400px;
  height: 200px;
  display:inline-block;
  overflow:hidden;
  position:relative;
}
.box:before,
.box:after{
  content:"";
  position:absolute;
  top:0;
  left:0;
  right:50%;
  bottom:0;
  background:
    radial-gradient(100% 116.3% at top   right, transparent 99%,#fff 100%) top,
    radial-gradient(100% 116.3% at bottom left, #fff 99%,transparent 100%) bottom;
  background-size:100% 50%;
  background-repeat:no-repeat;
}
.box:after {
  right:0;
  left:50%;
  transform:scaleX(-1);
}

body {
  background:linear-gradient(to right, purple, blue);
}

<div class="box">

</div>

You can then adjust left/right/bottom properties to control the overal shape by having some oveflow and overlap:

.box {
  width: 400px;
  height: 200px;
  display:inline-block;
  overflow:hidden;
  position:relative;
}
.box:before,
.box:after{
  content:"";
  position:absolute;
  top:0;
  left:-2px;
  right:40%;
  bottom:-45%;
  background:
    radial-gradient(100% 116.3% at top   right, transparent 99%,#fff 100%) top,
    radial-gradient(100% 116.3% at bottom left, #fff 99%,transparent 100%) bottom;
  background-size:100% 50%;
  background-repeat:no-repeat;
}
.box:after {
  right:-2px;
  left:40%;
  transform:scaleX(-1);
}

body {
  background:linear-gradient(to right, purple, blue);
}

<div class="box">

</div>

---

Here is an idea using SVG to replace the radial-gradient:

.box {
  height: 200px;
  overflow:hidden;
  position:relative;
}
.box:before,
.box:after{
  content:"";
  position:absolute;
  top:0;
  left:0;
  right:50%;
  bottom:0;
  background:url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" preserveAspectRatio="none"><path fill="white" d="M64 64 C56 30 8 48 0 0 L0 64 Z"/></svg>');
  background-size:100% 100%;
}
.box:after {
  right:0;
  left:50%;
  transform:scaleX(-1);
}

body {
  background:linear-gradient(to right, purple, blue);
}

<div class="box">

</div>

Here is a good online tool to edit the SVG: http://jxnblk.com/paths/. Simply append the path to the url at the end and edit it;

http://jxnblk.com/paths/?d=M64 64 C56 30 8 48 0 0 L0 64 Z