#calc-screen {
    margin: 20px;
    padding: 5px;
    outline: 1px solid #000000;
    width: 210px;
    text-align: right;
}

#calc-btns {
    margin: 20px;
}

#numbers {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    width: 120px;
    float: left;
}
#numbers button {
    /* unrounds corners */
    border-radius: 0%;
    /* removes shadow */
    border-style: solid;

    width: 40px;
    height: 40px;
}

#operations {
    display: flex;
    flex-wrap: wrap;
    width: 80px;
    float: left;
    margin-left: 20px;
}
#operations button {
    /* unrounds corners */
    border-radius: 0%;
    /* removes shadow */
    border-style: solid;

    width: 40px;
    height: 40px;
}