/* styles.css */
body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f0f0f0;
    color: #333;
}

header {
    background-color: #4CAF50;
    color: #fff;
    padding: 10px 0;
    text-align: center;
}

nav ul {
    list-style-type: none;
    padding: 0;
}

nav ul li {
    display: inline;
    margin: 0 15px;
}

nav ul li a {
    color: #fff;
    text-decoration: none;
}

main {
    padding: 20px;
}

section {
    margin-bottom: 40px;
}

.calculator {
    width: 320px;
    margin: 0 auto;
    background-color: #fff;
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.1);
}

#display {
    width: 100%;
    height: 60px;
    border: none;
    background-color: #222;
    color: #fff;
    font-size: 2em;
    text-align: right;
    padding: 10px;
    border-radius: 10px 10px 0 0;
}

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

button {
    height: 60px;
    font-size: 1.5em;
    border: none;
    border-radius: 5px;
    background-color: #f9f9f9;
    cursor: pointer;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #e0e0e0;
}

button:active {
    background-color: #d0d0d0;
}

button:nth-child(4n) {
    background-color: #ff9500;
    color: #fff;
}

button:nth-child(4n):hover {
    background-color: #e08900;
}

button:nth-child(4n):active {
    background-color: #c07800;
}

footer {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 10px 0;
    position: fixed;
    width: 100%;
    bottom: 0;
}