body
{
    padding: 0;
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: #94ccf7;
}
.container
{
    width: 45%;
    height: 45vh;
    padding: 10px;
    border-radius: 8px;
    box-shadow: 12px 12px 20px #e1ebf4,
                 -12px -12px 20px #ffff;
}
.display #screen
{
    width: 97%;
    height: 70px;
    font-size: 35px;
    outline: none;
    border: none;
    text-align: right;
    padding-right: .5em;
    background: #ecf0f3;
    border-radius: 6px;
    box-shadow:  inset 8px 8px 8px #cbced1,
                  inset -8px -8px 8px #cbced1;
}

.btns 
{
    width: 100%;
    margin: 1.7em;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}

.btns .row button 
{
    width: 80px;
    height: 30px;
    font-size: 20px;
    border: none;
    outline: none;
    margin: 5px;
    border-radius: 4px;
    box-sizing: 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: #33ccff;
    font-size: 14px;
    color: #ffff;
    box-shadow: inset 5px 5px 8px #66d9ff,
                inset -5px -5px 8px #00ace6;
}
#eval:hover
{
   box-shadow:  inset 5px 5px 8px #5bd1f8,
                 inset-5px -5px 8px #00ace6;
}

#ac
{
  background: #33cc33;
  color:#fff;

}
#ac:hover
{
    box-shadow:inset 5px 5px 8px #2eb82e,
               inset -5px -5px  8px #33cc33;
}
#ce
{
    background: #ff3399;
    color: #fff;
}
#ce:hover
{
    box-shadow: inset 5px 5px 8px #e60073,
                inset -5px -5px 8px #ff3399;
}