@media screen and (min-width: 900px){ 

  body {
    background-color: rgb(247 251 253);
    width: calc(100vw);
    height: calc(100vh);
    overflow: hidden;
    
  }
  
  .nav{
    height: 60px;
    background-color: rgba(255, 255, 255,0.4);
    box-shadow: 0px 1px 5px rgba(192, 192, 192, 0.815);
    backdrop-filter: blur(10px);
    display: flex;
    align-items: center;
    -webkit-backdrop-filter: blur(10px);
  }
  .nav img{
    margin-left: 100px;
    height: 35px;
  }
  
  .title {
    margin-top: -20px;
    font-size: 180%;
  }
  
  .middle{
    display: flex;
    justify-content: space-around;
    margin-left: calc(13vw);
    margin-right: calc(13vw);
    margin-top: 10%;
  }
   
  .hr{
    height:1px;
    color:var(--black);
    background-color: var(--black);
    -webkit-animation: slide-top 1s both;
    animation: slide-top 1.1s both;
    border: none;
    border-radius: 10px;
  }

  .pagetitle{
    line-height: 60px;
  }
  .placards-top{
    text-align: left;
    line-height: calc(6vh);
    font-size: calc(6vh);
    margin-bottom: 20px;
    -webkit-animation: slide-top 1s both;
    animation: slide-top 1s both;
    -moz-animation: slide-top 1s both;
    -o-animation: slide-top 1s both;
  }
  
  .placards-bottom{
    text-align: left;
    font-size: calc(3.5vh);
    line-height: calc(4vh);;
    margin-top: 10px;
    animation: slide-top 1.3s both;
    -moz-animation: slide-top 1.3s both;
    -webkit-animation: slide-top 1.3s both;
    -o-animation: slide-top 1.3s both;
  }
  
  .background{
    width: calc(70vh);
    height: calc(70vh);
    opacity: 1;
    background: linear-gradient(234.56deg, rgb(19, 140, 238) 0%, rgb(255, 167, 179) 100%);
    filter: blur(100px);
    border-radius: 100%;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
    z-index: -1;
    animation: ab 20s infinite;
    animation-delay: -1;
    transition:0.5s;
    -webkit-filter: blur(100px);
    -webkit-transition:0.5s;
    -moz-transition: 0.5s;
    -o-transition: 0.5s;
    -moz-animation: ab 20s infinite;
    -webkit-animation: ab 20s infinite;
    -o-animation: ab 20s infinite;
    -webkit-animation-delay: -1;
    -moz-animation-delay: -1;
    -o-animation-delay: -1;
  }
  
  .panel{
    background-color: rgba(255, 255, 255, 0.137);
    backdrop-filter: blur(10px);
    margin-left: 19%;
    margin-top:-5%;
    padding-left: 30px;
    padding-right: 30px;
    border: solid;
    border-color: rgba(236, 236, 236, 0.219);
    border-radius: 10px;
    transition: 0.5s;
    -webkit-backdrop-filter: blur(10px);
    -webkit-transition: 0.5s;
    -moz-transition: 0.5s;
    -o-transition: 0.5s;
  }
  
  .panel:hover{
    transform:scale(1.005);
    box-shadow: 0px 0px 10px rgba(49, 49, 49, 0.479);
    -webkit-transform:scale(1.005);
    -moz-transform:scale(1.005);
    -o-transform:scale(1.005);
  }
  .div-btm{
    justify-content: space-around;
    display: flex;
  }
  .btm {
    border-radius: 5px;
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100px;
    height: 55px;
    background-color: rgba(245, 245, 245, 0.2);
    margin-bottom: 20px;
    color: rgb(36, 36, 36);
    border: solid 1px;
    border-color: rgba(223, 223, 223, 0.637);
    font-size: 120%;
    text-decoration: none;
    transition-duration:0.5s;
    margin-left:10px;
    -webkit-transition-duration:0.5s;
    -moz-transition-duration:0.5s;
    -o-transition-duration:0.5s;
  }
  
  .btm:hover{
    background-color: #f9fbfd;
    transform: scale(1.03);
    border: solid 1px;
    border-color:#9c9a9a;
    box-shadow: 0px 0px 10px rgba(49, 49, 49, 0.479);
    -webkit-transform: scale(1.03);
    -moz-transform: scale(1.03);
    -o-transform: scale(1.03);
  }
  
  .title{
    padding-top: 30px;
    padding-left: 20px;
    padding-bottom: 10px;
    font-weight: 500;
    font-size: 140%;
  }

  .footnote{
    position: fixed;
    bottom: 5px;
    text-align: center;
    left: 0;
    right: 0;
    font-size: 15px;
  }
  /* 鼠标指针css，来自https://zhuanlan.zhihu.com/p/351951477 */
  #cursor {
    position: fixed;
    width: 16px;
    height: 16px;
    background: #000;
    border-radius: 8px;
    opacity: 0.25;
    z-index: 10086;
    pointer-events: none;
    transition: 0.2s ease-in-out;
    transition-property: background, opacity, transform;
    -webkit-transition: 0.2s ease-in-out;
    -moz-transition: 0.2s ease-in-out;
    -o-transition: 0.2s ease-in-out;
    -webkit-transition-property: background, opacity, transform;
    -moz-transition-property: background, opacity, transform;
    -o-transition-property: background, opacity, transform;
  }
  
  #cursor.hidden {
    opacity: 0;
  }
  
  #cursor.hover {
    opacity: 0.1;
    transform: scale(2.5);
    -webkit-transform: scale(2.5);
    -moz-transform: scale(2.5);
    -o-transform: scale(2.5);
  }
  
  #cursor.active {
    opacity: 0.5;
    transform: scale(0.5);
    -webkit-transform: scale(0.5);
    -moz-transform: scale(0.5);
    -o-transform: scale(0.5);
  }
}