body {
      margin: 0;
      padding: 0.2rem;
    }
    .pagehead{
      display: block;
      text-align: center;
      border-top: 2px solid lightseagreen;
      background: linear-gradient(yellow, lightseagreen);
      padding: 0.2rem 0.2rem 0.2rem 0.2rem;
      float:center;
      margin: 0.5rem;
      font-size: 32px;
    }

    .case{
      background-color: lightyellow;
      padding: 0.3rem 1rem 0.3rem 1rem;
      margin: 0.1rem;
    }
    img{
        width:20vw;
        height:30vh;
    }
    .responsive-three-columns {
    display:flex;
    flex-wrap:wrap;
}

/* columns */
.responsive-three-columns > * {
    width:100%;
    /*padding:1rem;*/
    border:1px solid black;
}
@media (min-width:768px) {
    .responsive-three-columns > * {
        width:30%;
    }
}
#observation{
    background-color: rgb(184, 245, 184);
    padding: 10px 20px;
    margin-top: 1rem;

}