body{
    padding: 0;
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: #ecf0f3;
}
.container{
    width: 45%;
    height: 50vh;
    padding: 10px;
    border-radius: 8px;
    box-shadow: 12px 12px 20px #cbced1,
                -12px -12px 20px #ffffff;
}
.display #screen{
    width: 97%;
    height: 70px;
    font-size: 35px;
    outline: none;
    border: none;
    text-align: right;
    padding-right: .5rem;
    background: #ecf0f3;
    border-radius: 6px;
    box-shadow: inset 8px 8px 8px #cbced1,
                inset -8px 8px 8px #ffffff;
}
.btns{
    width: 100%;
    margin-top: 1.7rem;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}
.btns .row button{
    width: 80px;
    height: 30px;
    font-size: 16px;
    border: none;
    outline: none;
    margin: 5px;
    border-radius: 4px;
    box-shadow: 5px 5px 8px #00000020,
                -5px -5px 8px #ffffff;
                transition: 1s;
}
.btns .row button:hover{
    box-shadow: inset 5px 5px 8px rgba(16,16,16,.1),
                inset -5px -5px 8px #fff;
                background: #fff;
}
#eval{
    background-color: #33ccff;
    color: #fff;
    box-shadow: inset 5px 5px 8px #66d9ff,
    inset -5px -5px 8px #00ace6;
}
#eval:hover{
    box-shadow: inset 5px 5px 8px #00ace6,
    inset -5px -5px 8px #00ace6;
}
#ac{
    background-color: #33cc33;
    color: #fff;
}
#ac:hover{
    box-shadow: inset 5px 5px 8px #2eb82e,
    inset -5px -5px 8px #33cc33;
}
#ce{
    background-color: #ff3399;
    color: #fff;
}
#ce:hover{
    box-shadow: inset 5px 5px 8px #e60073,
    inset -5px -5px 8px #ff3399;
}
 @media (max-width: 768px) {
    .container {
        width: 80%;
        height: auto;
    }
    .btns .row button {
        width: 70px;
        height: 35px;
        font-size: 14px;
    }
    .display #screen {
        font-size: 28px;
        height: 60px;
    }
}

@media (max-width: 480px) {
    .container {
        width: 90%;
    }
    .btns .row button {
        width: 65px;
        height: 30px;
        font-size: 13px;
    }
    .display #screen {
        font-size: 25px;
        height: 55px;
    }
}