[css] Draw a curve with css

@Navaneeth and @Antfish, no need to transform you can do like this also because in above solution only top border is visible so for inside curve you can use bottom border.

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.box {_x000D_
  width: 500px;_x000D_
  height: 100px;_x000D_
  border: solid 5px #000;_x000D_
  border-color: transparent transparent #000 transparent;_x000D_
  border-radius: 0 0 240px 50%/60px;_x000D_
}
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<div class="box"></div>
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