* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html,
body {
  height: 100%;
  width: 100%;
  /* background-color: aqua; */
}

#page1 {
  height: 100%;
  width: 100%;
  background-color: rgba(10, 83, 178, 0.678);
  display: flex;
  align-items: center;
  justify-content: center;
}
#page2 {
  height: 100%;
  width: 100%;
  background-color: rgba(105, 13, 210, 0.473);
  display: flex;
  align-items: center;
  justify-content: center;
}
#page3 {
  height: 100%;
  width: 100%;
  background-color: rgb(17, 55, 99);
  display: flex;
  align-items: center;
  justify-content: center;
}

#box {
  height: 200px;
  width: 200px;
  background-color: crimson;
}