styles.css

body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: #f0f0f0;
    font-family: 'Arial', sans-serif;
    margin: 0;
}

.calculator {
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.1);
}

.display {
    background: #333;
    color: #fff;
    font-size: 2em;
    text-align: right;
    padding: 20px;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
}

.btn {
    border: none;
    padding: 20px;
    font-size: 1.5em;
    cursor: pointer;
    transition: all 0.3s ease;
    background: linear-gradient(145deg, #e6e6e6, #ffffff);
    box-shadow: 5px 5px 10px #bebebe, -5px -5px 10px #ffffff;
    margin: 5px;
    border-radius: 10px;
}

.btn:active {
    background: linear-gradient(145deg, #ffffff, #e6e6e6);
    box-shadow: inset 5px 5px 10px #bebebe, inset -5px -5px 10px #ffffff;
}

.btn.operator {
    background: linear-gradient(145deg, #f6d365, #fda085);
}

.btn.operator:active {
    background: linear-gradient(145deg, #fda085, #f6d365);
}

.btn.clear {
    grid-column: span 4;
    background: linear-gradient(145deg, #ff4b2b, #ff416c);
}

.btn.clear:active {
    background: linear-gradient(145deg, #ff416c, #ff4b2b);
}