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

body {
    font-family: 'Arial', sans-serif;
    background-color: #f0f0f0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

/* Calculator Styles */
.calculator {
    width: 350px;
    padding: 20px;
    background-color: #333;
    border-radius: 10px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
}

.calculator .display {
    background-color: #444;
    color: #fff;
    padding: 20px;
    font-size: 30px;
    text-align: right;
    border-radius: 10px;
    margin-bottom: 20px;
    min-height: 60px;
    display: flex;
    align-items: center;
    justify-content: flex-end;
}

.calculator .keys {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

.calculator .key {
    background-color: #555;
    color: #fff;
    padding: 20px;
    font-size: 24px;
    text-align: center;
    border-radius: 10px;
    transition: background-color 0.2s, transform 0.2s;
    box-shadow: 0 5px 10px rgba(0, 0, 0, 0.1);
}

.calculator .key:hover {
    cursor: pointer;
}

.calculator .key:active {
    background-color: #666;
    transform: scale(0.95);
}

.calculator .operator {
    background-color: #f39c12;
    color: #fff;
}

.calculator .operator:hover {
    background-color: #d87e00;
}

.calculator .clear {
    background-color: #e74c3c;
}

.calculator .clear:hover {
    background-color: #c0392b;
}

.calculator .equal {
    background-color: #2ecc71;
}

.calculator .equal:hover {
    background-color: #27ae60;
}