html {
    font-family: Quicksand, "sans-serif";
    font-weight: bold;
}

body {
    margin: 0;
    padding: 25px;
    background: linear-gradient(to right, #ff9900, #ffcc00);
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    box-sizing: border-box;
}

.calculator {
    display: grid;
    justify-content: center;
    align-content: center;
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: minmax(30%, auto) repeat(5, 1fr);
    width: 100%;
    max-width: 400px;
    aspect-ratio: 1 / 1.6;
}

.calculator > button {
    background-color: rgba(255, 255, 255, 0.45);
    border: 1px solid white;
    cursor: pointer;
    outline: none;
    font-family: inherit;
    font-size: 1.3rem;
    font-weight: inherit;
}

@media (hover: hover) {
    .calculator > button:hover {
        background-color: rgba(255, 255, 255, 0.74);
    }
}

.calculator > button:active {
    background-color: rgba(255, 255, 255, 0.89);
}

.span-two {
    grid-column: span 2;
}

.output {
    grid-column: 1 / -1;
    background-color: rgba(0, 0, 0, 0.68);
    padding: 20px;
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    flex-direction: column;
    word-wrap: break-word;
    word-break: break-all;
    letter-spacing: 0.1rem;
}

.previous-operand {
    color: #dedede;
}

.current-operand {
    color: white;
    font-size: 1.8rem;
}