.flex{
  padding: 2.5% 0;
  display: flex;
  flex-direction: row;
  background: mediumblue;
  justify-content: space-evenly;
  );
}
.flex > *{
  width: 8%;
  background: aquamarine;
  font-size: 24px;
  text-align: center;
border-radius: 20px;/*角の丸み*/

}
.flex,
.flex > *{
  border: 10px solid #d3d3d3;
}