html, body {
  width: 100%;
  height:100%;
}

body {
    background: linear-gradient(-45deg, #ee7752, #e73c7e, #23a6d5, #23d5ab);
    background-size: 400% 400%;
    animation: gradient 15s ease infinite;
}

@keyframes gradient {
    0% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
    100% {
        background-position: 0% 50%;
    }
}



h2{
  text-align: center;
  margin-top: 50px;
}
.container {
  box-shadow: rgba(0, 0, 0, 0.4) 0px 30px 90px;
  width: 309px;
  margin: auto;
  border-radius: 10px;
    margin-top: auto;
  height: 350px;
  margin-top: 50px;}
  #screen {
    width: 243px;
    height: 32px;
    border-radius: 8px;
    font-size: 18PX;
    background-color: rgb(238, 136, 207);
    color: aliceblue;
    margin-top: 50px;
  }
  #clear {
    width: 251px;
    height: 35px;
    margin-top: 13px;
    margin-bottom: 13px;
    background-color: rgb(19, 87, 188);
    cursor: pointer;
    font-size: 18px;
    border: 1px solid rgb(246, 242, 242);
    border-radius: 8px;
  }

.button {
    width: 51px;
    margin: 5px;
    background-color: rgb(109, 233, 204);
    height: 30px;
    cursor: pointer;
    font-size: 20px;
    font-weight: bold;
    border-radius: 8px;
  
  }