body {
  background-image: url("https://www.visitspacecoast.com/sites/default/files/styles/large_image_s/public/2019-05/differet_about_sc_beaches_blog_image.jpg?itok=uDlvCxFS");
  background-image: no-repeat;
}

h1 {
  color: rgba(0, 0, 0, .3);
}

#box {
  position: absolute;
  top: 350px;
  left: 100px;
  height: 100px;
  width: 100px;
  border: 1px solid red;
  background-color: white;
  opacity: .3;
}