* {
  box-sizing: border-box;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  margin: 0;
}

.box {
  height: 500px;
  width: 500px;
  border: 10px solid brown;
  display: flex;
  flex-direction: column;
  

}

.row {
  display: flex;
  flex: 1; 
}

.col {
  flex: 1;
  /* border: 1px solid black; */
  
}