.top{ position: fixed; top:0px; background: #f9f9fb; width: 100%; z-index: 1000;}
.about-left{ 
    position: fixed; top:220px; padding: 0.5rem; width: 200px; border-radius: 10px; transition: all 0.3s;
    background: linear-gradient(
        180deg,
        #ffffff 0%,
        #f8f9fa 50%,
        #e9ecef 100%
    );
   
    box-shadow: 2px 0 5px rgba(0, 0, 0, 0.05);
}
.about-left h2{ font-size:1rem; line-height: 1.75rem; padding: 0.25rem 0.5rem;}
.about-left h2.active{
    color: #fff;
    background-color:var(--bs-gray-700);
    /* 背景设置一个透明度 */
    opacity: 0.8;
    border-radius: 6px;
}
.about-left h2.active a{
    color: #fff !important;
}
.about-left h2.active a:visited{
    color: #fff;
}

.about-main{ margin-top:150px; margin-left:240px;}
@media screen and (max-width: 992px) and (min-width: 768px) {
    .about-left{
        width: 135px;
        padding: 0 0.25rem;
    }
    .about-left a{
        font-size: 0.875rem;
    }
    .about-main{
        margin-left: 150px;
        font-size: 0.875rem;
    }
}

@media (max-width: 769px) {
    .about-left {
        width: 35px;
        padding: 0 0.25rem;
        left:5px;
        background-color: #fff;
        box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    }
    .about-left h2{
        padding: 0.25rem;
        text-align: center;
        line-height: 1rem;
        border-radius: 4px;
    }
    .about-left span{
        display: none !important;
    }
   .about-main {
        margin-left: 25px;
        margin-top: 190px;
        font-size: 0.875rem;
    }
}