html, body {
    height: 100%;
    margin: 0;
}
#wrapper {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}
main {
    flex: 1;
}
footer {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 30px;                   
    padding: 20px 0;
    font-size: 14px;
    font-family: "Microsoft YaHei", sans-serif;
    color: #333;
}