*{
    text-align: center;
    user-select: none;
}

#container {
    min-height: 100%; /* 2. 需要将容器的高度设置成100% */
    position: relative; /* 3. 容器的position设置为relative，给子元素定位提供基点 */
}

#content-wrap {
    padding-bottom: 2.5rem;  
}

.div1{
    display: flex;
    align-items: center;
    justify-content: center; 
}

.box {
    width: 500px;
    height: 500px;
    border: none;      
    padding: 0;       
    margin: 0;      
}

.box img {
    max-width: 75%;
    max-height: 75%;
    border-radius: 60px;
}

.box a{
    text-decoration: none;
    color: blue;
}

.box a:hover{
    color: black;
}

footer {
    position: absolute;
    bottom: 0;
    width: 100%;
    height: 2.5rem; 
    color: black;
}

.welcome{
    margin-bottom: 0;
}
.p1{
    margin-top: 0;
    margin-bottom: 30px;
    text-align: center;
    color: gray;
}