style.css

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body{
    display: flex;
    justify-content: center;
    margin-top: 5%;
    color: white;
}
.container {
    width: 22vw;
    height: 70vh;
    border: solid 2px black;
    border-radius: 30px;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: repeat(8, 1fr);
    grid-gap: 2%;
    padding: 2%;
    background-color: black;
}
.visor {
    grid-column-start: 1;
    grid-column-end: 5;
    grid-row-start: 1;
    grid-row-end: 4;
    border: 3px solid #353636;
    border-radius: 1rem;
    font-size: 5em;
    display: flex;
    justify-content: flex-end;
    align-items: center;
    padding-right: 1rem;
}
.zero {
    grid-column-start: 1;
    grid-column-end: 3;
    grid-row-start: 8;
    grid-row-end: 9;
}
.ac, .plusminus, .percentage {
    background-color: #A4A3A4;
    color: black;
}
.division, .multiplication, .minus, .plus, .equal {
    background-color: #FFA600;
}
.one, .two, .three, .four, .five , .six, .seven, .eight, .nine, .zero, .point {
    background-color: #353636;
}

button {
    border-radius: 50%;
    margin: 0 auto;   
    width: 5rem;
    height: 5rem;
    display: flex;
    justify-content: center;
    align-items: center;
    border: none;
    color: white;
    font-size: 2em;
}
#zero {
    align-self: stretch;
    width: 10rem;
    border-radius: 3rem;
}