*, *::before, *::after {
    box-sizing: border-box;
    font-family: sans-serif;
}

body {
    margin: 0;
    padding: 0;
    background: linear-gradient(to right, #00AAFF, #00FF6C);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.calculator {
    background-color: #333;
    border-radius: 10px;
    padding: 20px;
    display: grid;
    grid-template-columns: repeat(4, 80px);
    grid-template-rows: minmax(100px, auto) repeat(5, 80px);
    gap: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.5);
}

.display {
    grid-column: 1 / -1;
    background-color: #222;
    padding: 10px;
    border-radius: 5px;
    text-align: right;
    word-wrap: break-word;
    word-break: break-all;
}

.previous-operand {
    color: rgba(255, 255, 255, 0.75);
    font-size: 1.5rem;
    min-height: 30px;
}

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

button {
    font-size: 2rem;
    border: none;
    border-radius: 5px;
    background-color: #666;
    color: white;
    cursor: pointer;
}

button:hover {
    background-color: #999;
}

button[data-action="clear"] {
    background-color: #ff4444;
}

button[data-action="equals"] {
    background-color: #2196F3;
}

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

button[data-operator] {
    background-color: #FFA500;
}