body{
    display: flex;
    justify-content: center;
    align-items: center;
    background: cyan;
    min-height:  100vh;
}

#calculator_body{
    background: darkslategrey;
    width: fit-content;
    margin: 0 auto;
    padding: 26px 16px 26px 16px;
    border-radius: 5%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    row-gap: 20px;
}

.screen{
    background:rgb(12, 217, 135);
    height: 100px;

    display: block;
    box-sizing: border-box;
    width: 0;
    min-width: 100%;
    border-radius: 10px;

    text-align: end;
    font-size: 4rem;
}

#buttons_holder{
    display: grid;
    /* 3 columnas de igual tamaño */
    grid-template-columns: repeat(4, 1fr);
    gap: 5px;
    padding: 0px;
}

.keys{
    background: gray;
    height: 100px;
    width: 100px;
    border-radius: 25%;
    box-shadow: 0 2px 2px rgba(0, 208, 255, 0.701);
    font-size: 3rem;
    text-align: center;
}

.keys:hover{
    background: lightgray;
}

.control{
    background:coral;
}

.control:hover{
    background: lightcoral;
}

.operator{
    background:rgb(0, 255, 166);
}
.operator:hover{
    background:rgb(38, 221, 93);
}

.equals{
    background: cyan;
}
.equals:hover{
    background: lightcyan;
}

.polarity{
    background: yellow;
}