How to create a curve on the top of a background?

Question

Please help me change the cutout from .top so that it is on top and not on the right. As shown in the image. Thank you very much in advance. I really hope for your help, I'm new to this business. Source code: Source code

.box {
  margin-top:120px;
  width:200px;
  height:100px;
  background:white;
}
.box .top {
  height:100px;
  width:150px;
  transform:translateY(-100%);
  position:relative;
  background:#fff;
}

.top:before,
.top:after{
  content:"";
  position:absolute;
  top:0;
  width:50px;
  left:100%;
  bottom:50%;
  background:
    radial-gradient(100% 50% at top left, #fff 98%,transparent 100%) right,
    radial-gradient(100% 50% at bottom right, transparent 98%,#fff 100%) left;
  background-size:50% 100%;
  background-repeat:no-repeat;
}
.top:after {
  transform-origin:bottom;
  transform:scaleY(-1);
}
body {
  background:pink;
}

<div class="box">
<div class="top"></div>
</div>

Answer 1

You can adjust your code like below:

.box {
  margin-top:90px; /* make it at lealst the same as the height of the pseudo element */
  width:200px;
  height:100px;
  background:white;
  position:relative;
}

.box:before,
.box:after{
  content:"";
  position:absolute;
  bottom:100%;
  width:50%;
  left:0;
  height:80px; /* adjust this to control the height */
  background:
    radial-gradient(50% 100% at bottom left, #fff 98%,#0000) top,
    radial-gradient(50% 100% at top right  , #0000 98%,#fff) bottom;
  background-size:100% 50%;
  background-repeat:no-repeat;
}
.box:after {
  transform-origin:right;
  transform:scaleX(-1);
}
body {
  background:pink;
}

<div class="box">
</div>