* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    overflow: hidden;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;

    color: rgba(255, 255, 255, 0.8);
    font: bold 1rem Arial, sans-serif;

    background-color: rgb(20, 20, 20);

    height: 100vh;
    width: 100vw;
}

button {
    transition: .2s;

    width: 100%;
    min-width: 70px;
    max-width: 90px;

    height: 100%;
    min-height: 70px;
    max-height: 90px;

    cursor: pointer;
    
    color: inherit;
    background-color: transparent;

    border: none;
    border-radius: 50%;

    font-size: 1.4rem;
    font-weight: bold;
}

.container{
    background-color: rgba(12, 12, 12, 1);

    text-align: center;

    padding: 2%;

    border-radius: 20px;

    width: 100%;
    min-width: 340px;
    max-width: 460px;

    height: 100%;
    min-height: 660px;
    max-height: 760px;

    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: .6rem;
    grid-auto-rows: 1fr;
    justify-items: center;
}

.display, .output {
    grid-column: 1 / -1; 
    margin-right: 2%;

    width: 100%;
    height: 100%;
    
    text-align: center;
    overflow: auto;
}

.display { justify-self: right; }

.grey {
    background-color: rgba(255, 255, 255, 0.1);
}
.grey:hover { background-color: rgba(255, 255, 255, .08) }

.zero { 
    grid-column: span 2; 
    max-width: 100%;
    border-radius: 30px;
}

.lightgrey {
    color: rgba(0, 0, 0, 0.8);
    background-color: rgb(140, 140, 140);
}
.lightgrey:hover { background-color: rgba(140, 140, 140, .7); }

.orange{
    font-size: x-large;
    background-color: rgb(220, 120, 20);
}
.orange:hover { background-color: rgb(220, 120, 20, .7); }