*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body{
    display: flex;
    text-align: center;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background:linear-gradient(#729aa3, #1270bc , #20565d) ;
}
.center{
    width: 350px;
    background: black;
    border-radius: 20px;
}
input[type="text"] {
    height: 60px;
    width: 300px;
    margin-top: 40px;
    border-radius: 1px;
    border: 1px solid #e1e7ea;
    color: black;
    font-size: 22px;
    font-weight: bold;
    text-align: right;
    padding-right: 20px;
    background: linear-gradient(#d1dce0, #dfe6e9);
}
form .buttons{
    width: 300px;
    margin: 10px 25px 0 25px;
    padding: 10px 0;
}
input[type="button"] {
    width: 58px;
    height: 55px;
    margin: 5px;
    font-size: 22px;
    line-height: 55px;
    border-radius: 3px;
    border: 1px solid #d9d9d9;
    background: linear-gradient(#d9d9d9, #bfbfbf);
}

input[type="button"]:hover {
    transition: 0.5s;
    background: linear-gradient(#696767, #48a56c);
}
input#clear{
    background: #0d5107;
    border: 1px solid #0a4a05;
    color: white;
}
input#equal{
    width:275px;
    margin: 10px 0 10px 0;
    font-size: 30px;
    color: white;
    background: #0d5107;
    border: 1px solid #0a4a05;
}