Wave CSS

main.html

<div id="wave"></div>

style.css

#wave {
  position: relative;
  height: 70px;
  width: 100%;
  background: #e0efe3;
}

#wave:before {
    content: "";
    display: block;
    position: absolute;
    border-radius: 100% 50%;
    width: 47%;
    height: 80px;
    background-color: white;
    right: -5px;
    top: 40px;
}

#wave:after {
    content: "";
    display: block;
    position: absolute;
    border-radius: 100% 50%;
    width: 60%;
    height: 70px;
    background-color: #e0efe3;
    left: 0;
    top: 27px;
}