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

.calculator {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: minmax(100px, auto) repeat(5, 1fr);
    gap: .5rem;
    width: 100vw;
    height: 100vh;
    padding: 10px;
    border-radius: 20px;
    transition: all 0.4s;
    z-index: 100;
}

.display {
    grid-column: span 4;
    color: white;
    font-size: 3rem;
    display: flex;
    justify-content: flex-end;
    align-items: center;
    padding: 0.5rem;
    border-radius: 10px;
    position: relative;
    /* Allows us to absolutely position child elements */
    overflow: hidden;
    /* Hide characters when they move outside the display */
}

.display-text span {
    position: absolute;
    opacity: 0;
    top: 50%;
    transform: translateY(-100%);
    /* Vertically centered */
    font-size: 2.5rem;
    white-space: nowrap;
    color: white;
}

.display-text {
    position: relative;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: flex-end;
    /* Characters start from the right */
}

.button {
    background-color: var(--button-primary);
    border: none;
    border-radius: 50%;
    color: white;
    font-size: 1.25rem;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: .5rem;
    aspect-ratio: 1;
    /* This will make the buttons perfectly circular */
    cursor: pointer;

    transition: transform 0.1s ease-out;
}

.button.operation {
    background-color: var(--button-secondary);
}

.button.settings {
    background-color: var(--button-settings);
    border-radius: 50%;
}

.button.settings img {
    width: 1.5rem;
    height: 1.5rem;
}

.button:active {
    transform: scale(0.85);
}

.button.zero {
    grid-column: span 1;
    /* Make the '0' button normal size again */
}