body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: linear-gradient(135deg, #1d2671, #c33764);
    font-family: 'Segoe UI', sans-serif;
}

/* Calculator Box */
.calculator {
    background: #111;
    padding: 20px;
    border-radius: 20px;
    box-shadow: 0 0 30px #ff4b2b;
    text-align: center;
}

.calculator h2 {
    color: #ff4b2b;
    margin-bottom: 10px;
}

/* Display */
#display {
    width: 100%;
    height: 60px;
    margin-bottom: 15px;
    font-size: 24px;
    text-align: right;
    border: none;
    border-radius: 10px;
    padding: 10px;
    background: #000;
    color: #00ffcc;
}

/* Buttons Grid */
.buttons {
    display: grid;
    grid-template-columns: repeat(4, 70px);
    gap: 10px;
}

/* Buttons */
button {
    height: 60px;
    border: none;
    border-radius: 10px;
    font-size: 18px;
    cursor: pointer;
    background: #333;
    color: white;
    transition: 0.3s;
}

button:hover {
    background: #ff4b2b;
    transform: scale(1.1);
}

/* Equal Button */
.equal {
    background: #ff4b2b;
    color: white;
}

/* Zero Button */
.zero {
    grid-column: span 2;
}