body {
    background-color: lightgray;
    margin: 0px;
    border: solid red 3px;
    padding: 0px;
    box-sizing: border-box;
    overflow-x: hidden;
    overflow-y: hidden;
}

h1 {
  margin: 0px;
  text-align: center;
}

h3 {
  margin: 0px;
  text-align: center;
}



#center-window,
#right-window,
#top-window,
#bottom-window,
#left-window {
  margin: 0;
  padding: 25px;
  box-sizing: border-box;
  position: absolute;
  top: 0px;
  left: 0px;
}

#left-window {
  background-image: linear-gradient(120deg, #89f7fe 0%, #66a6ff 100%);
}

#center-window {
  background-color: lightblue;
}

#right-window {
  background-color: lightpink;
}

#top-window {
  background-color: red;
}

#bottom-window {
  background-color: blue;
}