/* 公共样式 */
body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
}

header {
    background-color: #333;
    color: white;
    padding: 10px 0;
    text-align: center;
}

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

/* 中心对齐文本 */
.center-text {
    text-align: center;
}

/* 留言板样式 */
.message-board {
    background-color: white;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    margin: 50px auto;
    max-width: 800px;
    padding: 20px;
}

.message-board h2 {
    font-size: 24px;
    margin-bottom: 20px;
}

.message-board form {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.message-board input[type="text"],
.message-board textarea {
    border: 1px solid #ccc;
    border-radius: 5px;
    padding: 10px;
    font-size: 16px;
}

.message-board textarea {
    resize: vertical;
    height: 100px;
}

.message-board button {
    background-color: #007bff;
    border: none;
    border-radius: 5px;
    color: white;
    cursor: pointer;
    padding: 10px;
    font-size: 16px;
}

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

#messages {
    margin-top: 20px;
    text-align: left;
}

#messages .message {
    background-color: #f9f9f9;
    border: 1px solid #ccc;
    border-radius: 5px;
    margin-bottom: 10px;
    padding: 10px;
}

#messages .message .username {
    font-weight: bold;
}