/* style.css */
body {
    margin: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #121212;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.calculator {
    background-color: #1e1e1e;
    border-radius: 20px;
    box-shadow: 0 0 20px rgba(0,0,0,0.7);
    width: 320px;
}

.display {
    background-color: #2c2c2c;
    color: #fff;
    font-size: 2.5rem;
    text-align: right;
    padding: 20px;
    border-top-left-radius: 20px;
    border-top-right-radius: 20px;
    overflow-x: auto;
}

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

.btn {
    padding: 20px;
    font-size: 1.5rem;
    border: 1px solid #333;
    background-color: #2c2c2c;
    color: #fff;
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn:hover {
    background-color: #3e3e3e;
}

.btn:active {
    background-color: #555;
}

.operator {
    background-color: #ff9500;
    color: #fff;
}

.operator:hover {
    background-color: #e08900;
}

.equal {
    background-color: #00b894;
    color: #fff;
    grid-row: span 2;
}

.equal:hover {
    background-color: #009f7f;
}

.clear {
    background-color: #e74c3c;
}

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

.zero {
    grid-column: span 2;
}