* {
  margin: 0;
  padding: 0;
}

body {
  display: flex;
  flex-direction: column;
  justify-content: center;  
  align-items: center;
  height: 100vh;
}

.parent {
  display: flex;
  flex-direction: column;
  justify-content: space-around;
  align-items: center;
  width: 90%;
  height: 95vh;
  border: 5px solid green;
}

.red {
  border: 5px solid red;
  width: 95%;
}

.blue {
  border: 5px solid blue;    
}

.yellow {
  border: 5px solid yellow;  
}

.red:nth-child(1),
.red:nth-child(4),
.red:nth-child(2),
.red:nth-child(3)  {  
  display: flex;
  align-items: center;
  justify-content: space-around;
}

.red:nth-child(1) .blue:nth-child(3),
.red:nth-child(4) .blue:nth-child(1),
.red:nth-child(3) .blue:nth-child(2) {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-around;
}

.red:nth-child(1),
.red:nth-child(4) {
  height: 15%;
}

.red:nth-child(1) .blue:nth-child(1),
.red:nth-child(1) .blue:nth-child(3),
.red:nth-child(4) .blue:nth-child(1),
.red:nth-child(4) .blue:nth-child(3) {
  width: 20%;
}

.red:nth-child(1) .blue:nth-child(2),
.red:nth-child(4) .blue:nth-child(2) {
  width: 50%;
}

.red:nth-child(1) .blue,
.red:nth-child(4) .blue {
  height: 70%;
}

.red:nth-child(1) .blue:nth-child(3) .yellow,
.red:nth-child(4) .blue:nth-child(1) .yellow {
  width: 80%;
  height: 30%;
}

.red:nth-child(2) {
  height: 10%;  
}

.red:nth-child(2) .blue {
  height: 60%;
}

.red:nth-child(2) .blue:nth-child(1),
.red:nth-child(2) .blue:nth-child(4) {
  width: 25%;
}

.red:nth-child(2) .blue:nth-child(2),
.red:nth-child(2) .blue:nth-child(3) {
  width: 20%;
}

.red:nth-child(3) {
  height: 50%;  
}

.red:nth-child(3) .blue {
  height: 90%;
}

.red:nth-child(3) .blue:nth-child(1) {
  width: 20%;
}

.red:nth-child(3) .blue:nth-child(2) {
  width: 70%;  
}

.red:nth-child(3) .blue:nth-child(2) .yellow {
  width: 90%;
}

.red:nth-child(3) .blue:nth-child(2) .yellow:nth-child(1) {
  height: 70%;
}

.red:nth-child(3) .blue:nth-child(2) .yellow:nth-child(2) {
  height: 15%;
}