* {
    margin: 0;
    padding: 0;
    font-family: Verdana, Geneva, Tahoma, sans-serif;
}

body {
    background: url(bg.jpg);
    background-size: cover;
    background-repeat: no-repeat;
}

div.calculator {
    border-radius: .4rem;
    box-shadow: 4px 12px 12px rgba(0, 0, 0, 0.5), 5px 15px 200px rgba(0, 0, 0, 0.5);
    position: absolute;
    top: 50%;
    left: 50%;
    padding: 0.5rem;
    transform: translate(-50%, -50%);
    background-color: white;
    display: grid;
    grid-template-columns: repeat(4, 5rem);
    grid-template-rows: 2rem repeat(7, auto);
    grid-gap: 1rem;
}

.items {
    outline: none;
    background-color: white;
    border: none;
    border-radius: 100%;
    font-size: large;
    font-weight: 200;
    line-height: 5rem;
    text-align: center;
    align-items: center;
    transition: .4s all ease;
    cursor: pointer;
}

.items:hover {
    background-color: white;
}

button.items:active {
    transform: translateY(-12px);
}

.items0 {
    text-align: right;
    color: #888888;
    grid-area: 1/1/2/-1;
    border-radius: 0;
}

.items1 {
    height: 6rem;
    font-size: 2.5rem;
    border-radius: 1rem;
    line-height: 6rem;
    text-align: right;
    grid-area: 2/1/3/-1;
}

.items0,
.items1 {
    padding: 0 1.2rem;
}

.items1:hover,
.items0:hover {
    cursor: auto;
}

.items2 {
    background-color: tomato;
}

.items5 {
    background-color: #0f9b3d;
}

.items9 {
    background-color: #FDC201;
}

.items13 {
    background-color: #E83C88;
}

.items17 {
    background-color: #00B1C3;
}

.items21 {
    background-color: #802872;
}

span.items.items18,
span.items.items20 {
    font-family: cursive;
    color: orangered;
    font-size: 1.2rem;
    font-weight: 700;
    cursor: auto;
    transition: .3s all ease;
    transition-duration: 1s;
}
span.items.items18:hover,
span.items.items20:hover {
    transform: rotate(360deg);
    color: orchid;
}

@media only screen and (max-width: 922px) {
    body {
        background: url(bg-small.jpg);
        background-size: cover;
        background-repeat: no-repeat;
    }
}