html, body {
    margin: 0;
}

body {
    display: flex;
    background: #f5f5f5;
}

.zong{

    display: flex;
    flex-direction: row;  /* 👈 关键：上下排列 */
    width: 100%;
    align-items: flex-start;
}
.container {
    position: sticky; 
    display: flex;
    width: 15%;
    flex-direction: column;  /* 👈 关键：上下排列 */
    top: 0 ;
}

.f{
    padding-top: 20px;
    font-size: 20px;
    color: #333;
    letter-spacing: 1px;
    margin-left: 15%;
    font-weight: 250;
}

.zhuye {
    text-decoration: none;
    color: #333;
}

.list {
    width: 100%;
}

.item {
    display: flex;
    align-items: flex-end; 
}

.num {
    font-size: 50px;
    font-weight: 200;
    color: #333;
    width: 80px;
}

.text {
text-decoration: none;
}

.text:hover .title{
    color: #5da0cc; /* 悬停变蓝 */
}

.text:hover .sub{
    color: #5da0cc; /* 悬停变蓝 */
}

.title {
    font-size: 10px;
    color: #333;
}

.sub {
    font-size: 8px;
    color: #666;
    margin-top: 6px;
    font-weight: 300;
}

.preview {
    flex: 1;
    position: relative;
    width: 100%;
    top: 60px;
    opacity: 1;
}
.preview img {
    margin-left: 5%;
    margin-bottom: 30px;
    width: 90%;
    border-radius: 8px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.2);
}
.preview img:hover {
    box-shadow: 0 15px 40px rgba(0, 140, 255, 0.3);
}
.item a.active{
    color: #48d1ff;
    font-weight: bold;
}
.tupian{
    opacity: 0;
    transform: translateY(40px);
    transition: all 1s ease;
}
.tupian.show{
    opacity: 1;
    transform: translateY(0);
}