.rechner {
    display: grid;
    margin: initial;
    width: 160px;
    border: 3px solid black;
    padding: 10px;
    box-shadow: 6px 6px 6px 1px #888888;
    background-color: yellow;
}

.display {
    margin: auto;
    padding: 1px;
}

    .display [type=text] {
        width: 155px;
        min-height: 40px;
        text-align: right;
        background-color: black;
        color: white;
        font-size: 24px;
    }

.tastatur {
    display: grid;
    grid-template-columns: 40px 40px 40px 40px;
    color: red;
}

.taste, .doppeltaste {
    text-align: center;
    display: contents;
    font-size: 16px;
    
}

.doppeltaste [type= button] {
    display: normal;
}


.taste [type=button] {
    color: white;
    background-color: black;
    height: 30px;
}

    .doppeltaste [type=button] {
        color: white;
        background-color: black;
        height: 30px;
        width: 80px;
    }

doppeltaste [type=button] {
    color: white;
    background-color: black;
}

.taste [type=button]:hover, .doppeltaste [type=button]:hover {
    color: red;
}

.doppeltaste [type="button"] {
    color: white;
    background-color: black;
}
.leer {
    visibility: hidden;
}