.container {
  color: black;
  position: absolute;
  width: 560px;
  height: 300px;
  padding: 25px;
  border: solid black 5px;
  top: 15%;
  left: 50%;
  transform: translate(-50%, -25%);
  background-color: white;
}
.border {
  height: 950px;
  margin: 10px;
  border: 15px solid;
}

body {
  background-color: red; /* For browsers that do not support gradients */
  background-image: linear-gradient(to right, red, yellow);
}