*, *::before, *::after {
    box-sizing: border-box;
    font-family: Gotham, "Helvetica Neue", Helvetica, Arial, "sans-serif";
    font-weight: normal;
}

body {
    padding: 0;
    margin: 0;
    height: 100vh;
    background-position: center;
    background-size: cover;
    background-image: linear-gradient(rgba(0,0,0,0.2),rgba(0,0,0,0.2)),url("background.jpg");
}

.calculator-grid {
    display: grid;
    justify-content: center;
    align-content: center;
    min-height: 100vh;
    grid-template-columns: repeat(4, 100px);
    grid-template-rows: minmax(120px, auto) repeat(5, 100px);
}

.operation {
    cursor: pointer;
    font-size: 2rem;
    border: 1px solid white;
    outline: none;
    background-color: rgba(92, 175, 255, 0.75);
}

.number {
    cursor: pointer;
    font-size: 2rem;
    border: 1px solid white;
    outline: none;
    background-color: rgba(255, 255, 255, 0.75);
}

.span-two {
    cursor: pointer;
    font-size: 2rem;
    border: 1px solid white;
    outline: none;
    background-color: rgba(255, 255, 255, 0.75);
}

.delete {
    cursor: pointer;
    font-size: 2rem;
    border: 1px solid white;
    outline: none;
    background-color: rgba(255, 147, 171, 0.75);
}

.calculator-grid > button:hover {
    background-color: rgba(255, 255, 255, 0.9);
}

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

.output {
    grid-column: 1/-1;
    background-color: rgba(0, 0, 0, 0.75);
    display: flex;
    align-items: flex-end;
    justify-content: space-around;
    flex-direction: column;
    padding: 10px;
    word-wrap: break-word;
    word-break: break-all;
}

.output .prev-operand {
    color: rgba(255, 255, 255, .75);
    font-size: 1.5rem;
}

.output .cur-operand {
    color: white;
    font-size: 2.5rem;
}