body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
}

header {
    background-color: #007BFF;
    color: white;
    padding: 15px 0;
    text-align: center;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
}

.header-container {
    max-width: 1200px;
    margin: auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
}

.nav-links {
    list-style: none;
    padding: 0;
    display: flex;
}

.nav-links li {
    margin: 0 15px;
}

.nav-links a {
    color: white;
    text-decoration: none;
    font-weight: bold;
}

.nav-links a:hover {
    text-decoration: underline;
}

main {
    padding: 20px;
}

.container {
    max-width: 500px;
    margin: auto;
    padding: 20px;
    background: #fff;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    text-align: center;
}

input[type="number"] {
    width: 100%;
    padding: 12px;
    margin: 15px 0;
    border: 1px solid #ccc;
    border-radius: 8px;
    font-size: 1em;
}

.button-group {
    display: flex;
    justify-content: space-around;
}

button {
    padding: 12px 20px;
    margin: 5px;
    border: none;
    border-radius: 8px;
    background-color: #007BFF;
    color: white;
    cursor: pointer;
    font-size: 1em;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #0056b3;
}

.result {
    margin-top: 20px;
    font-size: 1.5em;
    color: #333;
}

.info {
    margin-top: 20px;
    font-size: 0.9em;
    color: #555;
    text-align: left;
}

footer {
    background-color: #333;
    color: #fff;
    padding: 20px 0;
    text-align: center;
}

.footer-container {
    max-width: 1200px;
    margin: auto;
    padding: 0 20px;
}

.explanation {
    margin-bottom: 20px;
    font-size: 1em;
    color: #ddd;
    text-align: left;
}

.footer-links {
    margin-bottom: 10px;
}

.footer-links h4 {
    margin: 0 0 10px;
}

.footer-links ul {
    list-style: none;
    padding: 0;
    display: flex; /* 使用 flexbox 进行横向排列 */
    justify-content: center; /* 居中对齐 */
}

.footer-links li {
    margin: 0 15px; /* 设置左右间距 */
}

.footer-links a {
    color: #fff;
    text-decoration: none;
}

.footer-links a:hover {
    text-decoration: underline;
}