style.css

*{
    font-family:'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande', 'Lucida Sans Unicode', Geneva, Verdana, sans-serif;
    box-sizing:border-box;
    justify-content:center;
}
h1{
   text-decoration: underline;
   font-family: 'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande', 'Lucida Sans Unicode', Geneva, Verdana, sans-serif;
}
.container{
    width:100%;
    height:100vh;
    background: #e3f9ff;
    display: flex;
    align-items: center;
    justify-content: center;
}
.container2{
    background: #05071b;
    padding: 20px;
    margin:10px;
    border-radius: 50px;
}
.container form input{
    border:0;
    width: 70px;
    height:70px;
    border-radius: 50px;
    box-shadow: 8px -8px 10px rgba(255,255,255,0.1),6px 5px 8px rgba(233, 227, 227, 0.216);
    background: transparent;
    font-size: 25px;
    color:#ffff;
    cursor:pointer;
    margin:10px;
}
.link{
    display: flex;
    flex-wrap:wrap;
    justify-content: flex-start;
}
.btn1{
    color:bisque;
    background-color: #05071b;
    size: 10rem;
    font-size: 1rem;
}
form .display{
    display: flex;
    justify-content:flex-start;
    margin: 20px 0;
}
form .display input{
    text-align: right;
    flex:1;
}
form input.equal{
    color:white;
    background-color: orange;
    width:170px;
}
form input.operator{
    color:white;
    font-weight: bolder;
    background-color: rgb(91, 90, 90);
}
form input.btn{
background-color: rgb(56, 54, 54);
font-weight: bolder;
}
.foot{
    color:#05071b;
}