styles.css

body {
    font-family: 'Roboto', Arial, sans-serif;
    background: linear-gradient(135deg, #0073e6, #004080);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    color: #ffffff;
}

.calculator {
    background: #ffffff;
    width: 360px;
    border-radius: 15px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.display input {
    width: 100%;
    height: 60px;
    border: none;
    background: #f3f3f3;
    font-size: 2em;
    text-align: right;
    padding: 10px;
    border-radius: 10px;
    margin-bottom: 20px;
    color: #333;
    box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.1);
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 15px;
}

button {
    background: #0073e6;
    color: white;
    border: none;
    padding: 20px;
    font-size: 1.5em;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.2);
}

button:hover {
    background: #005bb5;
    transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.3);
}

button:active {
    transform: translateY(0);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.2);
}

button.equal {
    background: #00b300;
    grid-column: span 2;
}

button.equal:hover {
    background: #008f00;
}

button.zero {
    grid-column: span 2;
}

button:nth-child(1) {
    background: #ff4d4d;
}

button:nth-child(1):hover {
    background: #e60000;
}

button:nth-child(2) {
    background: #ffaa00;
}

button:nth-child(2):hover {
    background: #e69500;
}