body{
    background-color: rgb(165, 161, 161);
}
.container{
    width: 250px;
    height: 400px;
    margin: 80px auto;
    border-radius: 20px;
    background: rgb(229, 226, 226);
    box-shadow: 5px 5px 10px #b6a9a9, -5px -5px -10px #ffffff;
}
.cal-box{
    width: 200px;
    margin: 20px auto;
}
#display{
    border: none;
    outline: none;
    color: black;
    text-align: right;
    font-weight: 600;
    padding: 15px;
    margin: 30px 0 20px 0;
    background: transparent;
    box-shadow: inset 2px 2px 5px #babeec, inset -5px -5px 10px #ffffff;
}
.button{
    margin: 15px 0 0 5px;
    width: 42px;
    height: 42px;
    border: none;
    outline: none;
    font-size: 18px;
    font-weight: bold;
    cursor: pointer;
    border-radius: 8px;
    background: rgb(226, 223, 223);
    box-shadow: 5px 5px 10px #aca6a6, -5px -5px 10px #d3caca;
    display: inline-block;
}
.button:active{
    box-shadow: inset 1px 1px 2px #b6bbf1, inset -1px -1px 2px #fff;
}
.clearButton{
    background: red;
    color: white;
}
.mathbutton{
    background: black;
    color: white;
}

html,body{
    margin-top: 15px;
    display: grid;
    height: 100vh;
    place-items: center;
    background:  rgb(112, 109, 109);
}
.btn a{
    position: relative;
    color: #f5f5f5;
    height: 70px;
    width: 220px;
    display: block;
    text-align: center;
    border-radius: 10px;
    text-decoration: none;
    background-image: linear-gradient(115deg,#4fcf70,#fad648,#a767e5,#12bcfe,#44ce7b);
}
.btn a:hover{
    animation: rotate 0.3s linear infinite;
}
@keyframes rotate {
    100%{
      filter: hue-rotate(-360deg)
}
}
.btn a span{
    height: 88%;
    width: 96%;
    background: #111;
    display: block;
    position: absolute;
    top: 50%;
    left: 50%;
    border-radius: 6px;
    line-height: 62px;
    font-size: 25px;
    transform: translate(-50%, -50%);
}