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

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

.calculator-grid {
    display: grid;
    grid-template-columns: repeat(4, 100px);
    grid-template-rows: minmax(120px, auto) repeat(5, 100px);
    border: 2px solid #333;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
}

.calculator-grid > button {
    cursor: pointer;
    font-size: 2rem;
    border: 1px solid #555;
    outline: none;
    background-color: #f9f9f9;
    transition: background-color 0.2s;
}

.calculator-grid > button:hover {
    background-color: #eee;
}

.calculator-grid > button[data-operation] {
    background-color: #f7931b;
    color: white;
}

.calculator-grid > button[data-operation]:hover {
    background-color: #e6891a;
}

.calculator-grid > button[data-all-clear] {
    background-color: #d9534f;
    color: white;
}
.calculator-grid > button[data-all-clear]:hover {
    background-color: #c9302c;
}

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

.output {
    grid-column: 1 / -1;
    background-color: #333;
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    justify-content: space-around;
    padding: 20px;
    word-wrap: break-word;
    word-break: break-all;
}

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

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