body {
    margin: 0;
    background-image:radial-gradient(gray, black);;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    background-color: black;
}
input[type=text] {
  position: absolute;
  width: 96%;
  height: 40px;
  padding: 12px 20px;
  margin: 10px 2%;
  box-sizing: border-box;
  border-radius: 20px;
  border: none;
  background-color: white;
  color: black;
}
img {
    display:block;
    position:absolute;
    top:0;
    left:0;
    right:0;
    bottom:0;
    margin:auto;
    visibility:hidden;
}
.btn {
  display:block;
  position:absolute;
  right:2%;
  bottom:2%;
  height: 100px;
  width: 100px;
  border-radius: 50%;
  border: 1px solid red;
  color: white;
}
.buy {
    display:block;
    position:absolute;
    right:2%;
    bottom:2%;
  width: 100px;
  height: 100px;
  background-image: url("buy.png");
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
}