Draw a curve with css

Question

I want to create an animation with css that simulate a wave movement.
I need to change a line-or div- to a curve for this...
The CSS rules that I'm familiar to, make the entire div to semicircular or change element border.
For example: border-radius, or perspective or border-top-radius...
This image show you what I want:

Do you have experience about this? or is it possible?
Thanks in Advance...

Answer 1

You could use an asymmetrical border to make curves with CSS.

border-radius: 50%/100px 100px 0 0;

VIEW DEMO

.box {
  width: 500px; 
  height: 100px;  
  border: solid 5px #000;
  border-color: #000 transparent transparent transparent;
  border-radius: 50%/100px 100px 0 0;
}

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

Answer 2

@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.

.box {
  width: 500px;
  height: 100px;
  border: solid 5px #000;
  border-color: transparent transparent #000 transparent;
  border-radius: 0 0 240px 50%/60px;
}

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