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

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

#calc-container {
    width: 300px;
    height: auto;
    border: solid 2px black;
    padding: 2px;
}

#display {
    width: 100%;
    border: solid 1px brown;
    height: 100px;
    background-color: cornsilk;
    text-align: right;
    padding: 10px;
}

#calculation {
    padding: 5px 10px;
}

#result {
    padding: 5px 10px;
    font-size: 2em;
}

#rec-btns-container {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 2px;
}

.rec-btns {
    flex-grow: 1;
    aspect-ratio: 3/1;
    border-radius: 5px;
}

.rec-btns:hover {
    background-color: white;
}

#clr-btn {
    border: solid 1px lightcoral
}

#undo-btn {
    border: solid 1px sienna;
}

#sq-btns-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

.sq-btns {
    flex-grow: 1;
    aspect-ratio: 1/1;
    flex-basis: 25%;
    border-radius: 5px;
}

.sq-btns:hover {
    background-color: white;
}

.num-btns, #dec-btn {
    border: solid 1px orange;
}

.op-btns {
    border: solid 1px pink;
}

#eq-btn {
    border: solid 1px green;
}