body { padding-top: 56px;-webkit-text-fill-color: white; }
.left-aligned { margin-left: auto; }
/* .bg-dark { background: linear-gradient(to right,pink,purple)} */
.bg-hero { background-color:transparent }
/*头部导航栏变大*/
.fixed-top>.container{
    margin-bottom: 3px;
    margin-top: 3px;
}
/* CALLOUT */
.bd-callout { padding:1.25rem; margin-top:1.25rem; margin-bottom:1.25rem; border:1px solid #e9ecef; border-left-width:.25rem; border-radius:.25rem }
.bd-callout h4 { margin-bottom:.25rem }
.bd-callout p:last-child { margin-bottom:0 }
.bd-callout code { border-radius:.25rem }
.bd-callout+.bd-callout { margin-top:-.25rem }
.bd-callout-info { border-left-color:#5bc0de }
.bd-callout-warning { border-left-color:#f0ad4e }
.bd-callout-danger { border-left-color:#d9534f }

/* footer */
footer a { color: white; font-weight: bold; text-decoration: none; }
footer a:hover { color: white; text-decoration: underline; }
.dropdown-item{
    -webkit-text-fill-color: black !important;
}
html{
    scroll-padding-top: 60px;
} 
body {
    /* 加载背景图 */
    
    /* 背景图垂直、水平均居中 */
    background-position: center center;
    /* 背景图不平铺 */
    background-repeat: no-repeat;
    /* 当内容高度大于图片高度时，背景图像的位置相对于viewport固定 */
    background-attachment: fixed;
    /* 让背景图基于容器大小伸缩 */
    background-size: cover;
    /* 设置背景颜色，背景图加载过程中会显示背景色 */
    background-color: #464646;

    /* background-image: linear-gradient(to bottom, #0c3483 0%, #a2b6df 100%, #6b8cce 100%, #a2b6df 100%); */
    background-image: linear-gradient(to top, #09203f 0%, #537895 100%);
}

.btn a{
    -webkit-text-fill-color: black !important;
}
nav {
    background-image: linear-gradient(to right, #678BD6, #DEF8F1, #678BD6, #4569A4, #101A30);
    box-shadow: inset 0 0 5em rgba(0, 0, 0, 0.5);
    animation-duration: 20s;
    animation-iteration-count: infinite;
    animation-name: bolang;
    background-size: 487%;
}
@keyframes bolang {
    0% {
    background-position: 0 0;
    }
    25% {
    background-position: 50% 0;
    }
    50% {
    background-position: 90% 0;
    }
    60% {
    background-position: 60%;
    }
    75% {
    background-position: 40%;
    }
    100% {
    background-position: 0 0;
    }
}
h2{
font-weight: bold;
text-align: center;
margin-left: -3%;
margin-top: 3%;
}
div p,h3,h4{
    margin-left:5%;
    margin-right:5%;
}

div h3{
    margin-left:5%;
    margin-right:5%;
}
.des{
    box-shadow: rgba(0, 0, 0, 0.56) 0px 22px 70px 4px;
    margin-left: 4%;
    border-radius: 10px;
}
hr.style-five {

    border: 0;
    
    height: 0; /* Firefox... */
    
    box-shadow: 0 0 10px 1px #f0ad4e;;

    }
    .tree{
    position: relative;
    }
.tree-node{
    position:absolute;
    top:calc((var(--cc)*5%));
    left:56%;
    width: 28%;
    height: 7%;
}
.tree-node img {

    
    position: absolute;
    
    top: 0;
    
    left: 0;
    
    transition: all 1s;
    
    }
.tree-node:hover img {

    transform: rotateX(180deg);
    
    }

.tree-node img:first-child {
      z-index: 1; 
     backface-visibility: hidden; 
        }
    .edu-left{
        width: 85%;
    height: 100%;
    }
    .edu_pic{
        width:37%;
        position:relative;
        left:31%;
       }
       .tree-nodee{
        position:absolute;
        top:calc((var(--dd) * 5%) + 8%);
        left:20%;
        width: 28%;
        height: 7%;
    }
    .tree-nodee img {
    
        
        position: absolute;
        
        top: 0;
        
        left: 0;
        
        transition: all 1s;
        
        }
    .tree-nodee:hover img {
    
        transform: rotateX(180deg);
        
        }
    
    .tree-nodee img:first-child {
          z-index: 1; 
         backface-visibility: hidden; 
            }
            .clip{
                display: flex;
                justify-content: center;
                width: 100%;
                height: fit-content;
                flex-direction: row;
                flex-wrap: wrap;
            }
                .card-filp {
                    width: 320px;height: 400px;
                    position: relative;
                    transform-style: preserve-3d;
                    transition: 1s;
                    -moz-border-radius: 20px;-webkit-border-radius: 20px;border-radius: 20px;
                    margin:20px;
                  }
                  .card-filp-pi {
                    width: 320px;height: 400px;
                    position: relative;
                    transform-style: preserve-3d;
                    transition: 1s;
                    -moz-border-radius: 20px;-webkit-border-radius: 20px;border-radius: 20px;
                    margin:20px;
                  }
                  .front,
                  .back {
                    height: 100%;
                    width: 100%;
                    position: absolute;
                    left: 0;
                    top: 0;
                    backface-visibility:hidden
                  }
                  .front {
                    background: lightgreen;
                  }
                  .back {
                    background: lightblue;
                  }
                  .back {
                    transform: rotateY(180deg);
                  }
                  .card-filp:hover {
                    transform: rotateY(180deg);
                  }