#logo-video {
    margin-top: 10px;
    width: 200px;
    /* 根据需要调整视频的宽度 */
    height: auto;
    /* 自动调整高度，保持宽高比 */
}

body {
    margin: 0;
    padding: 0;
    height: 200vh;
    overflow-x: hidden;
}

.first {
    width: 100%;
    height: 100vh; /* Make it full viewport height */
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    position: relative;
}

.background {
    background-image: url(https://static.igem.wiki/teams/5730/wiki/s6.webp);
    background-size: 100% 100%;
    background-position: top center;
    background-repeat: no-repeat; /* 避免背景动图重复 *
    height: 100vh; /* 设置背景高度为视口高度 */
    width: 100%; /* 宽度填满屏幕 */
    font: 1000 16rem '';
    /* change the size and spacing of the word*/
    position: absolute;
    text-align: center;
    padding-top: 0px;
    padding-bottom: 0px;
}
.background {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    width: 100%;
    height: 100%;
}

.welcome-text {
    font-size: 1.5em;
    background: linear-gradient(45deg, #fff, #e9ec15);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    text-align: center;
    margin-top: 20px;
    letter-spacing: 3px;
    font-weight: bold;
    text-shadow: 2px 2px 8px rgba(0, 0, 0, 0.5);
    z-index: 2;
}

.welcome-text1 {
    font-size: 1.5em;
    background: linear-gradient(45deg, #ffe97a, #fff4be);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    text-align: right;
    margin-top: 20px;
    letter-spacing: 3px;
    box-sizing: border-box;
    font-weight: bold;
    text-shadow: 2px 2px 8px rgba(0, 0, 0, 0.5);
    z-index: 2;
}


.background h1{
    font-size: 200px;
    font-weight: bold;
    color: linear-gradient(45deg, #fff, #e9ec15);
    -webkit-background-clip: text;
    background-clip: text;
    color: white;
    text-shadow: 0 2px 5px rgba(0, 0, 0, 0.7);
}

h2 {
    position: absolute;
    letter-spacing: 2px;
    top: 120vh;
    width: 60%;
    color: #fff;
    left: 50%;
    transform: translateX(-50%);
    padding: 30px;
    background-color: rgba(0, 0, 0, .3);
}

#logo-video {
    position: absolute;
    top: 60%;
    /* 根据实际需求调整这个数值，使其定位到湖的区域 */
    left: 50%;
    /* 居中对齐视频 */
    transform: translate(-50%, -50%);
    /* 确保视频相对于中心位置居中 */
    width: 80%;
    /* 使用百分比来调整视频的大小，确保比例合适 */
    height: auto;
    /* 保持宽高比 */
    z-index: 2;
    /* 确保视频在背景图片的上层 */
}

.logo {
    text-align: center;
    position: relative;
    top: 50vh;
    /* 更靠近标题下方，适应视觉效果 */
}

.shell {
    width: 100%;
    position: relative;
    padding: 80px 0;
    transition: 0.3s ease 0s;
    background-attachment: fixed;
    background-size: cover;
}

.shell:before {
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background: rgba(99, 99, 99, 0.8);
    content: "";
}

.title {
    color: #fff;
    font-size: 46px;
    font-weight: normal;
    margin: 0;
}

.timeline {
    display: flex;
    margin: 0 auto;
    flex-wrap: wrap;
    flex-direction: column;
    max-width: 700px;
    position: relative;
}

.content-title {
    font-weight: normal;
    font-size: 50px;
    margin: -10px 0 0 0;
    transition: 0.4s;
    padding: 0 5px;
    box-sizing: border-box;
    color: #fff
}

.content-desc {
    margin: 0;
    font-size: 15px;
    font-weight: 600;
    width: 500px;
    display: flex;
    margin-left: 0px;
    background: linear-gradient(45deg, #66d35a, #83cee3);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    line-height: 40px;
}

.timeline:before {
    position:relative;
    left: 50%;
    width: 2px;
    height: 100%;
    margin-left: -1px;
    content: "";
    background: rgba(255, 255, 255, 0.07);
}

.item {
    padding: 40px 0;
    opacity: 0.3;
    filter: blur(2px);
    transition: 0.5s;
    box-sizing: border-box;
    width: calc(50% - 40px);
    display: flex;
    position: relative;
    transform: translateY(-80px);
}

.item:before {
    content: attr(data-text);
    letter-spacing: 3px;
    width: 100%;
    position: absolute;
    color: rgba(255, 255, 255, 0.5);
    font-size: 13px;
    border-left: 2px solid rgba(255, 255, 255, 0.5);
    top: 70%;
    margin-top: -5px;
    padding-left: 15px;
    opacity: 0;
    right: calc(-100% - 56px);
    font: 900 20px;
    letter-spacing: 5px;
}

.item:nth-child(even) {
    align-self: flex-end;
}

.item:nth-child(even):before {
    right: auto;
    text-align: right;
    left: calc(-100% - 56px);
    padding-left: 0;
    border-right: none;
    border-right: 2px solid rgba(255, 255, 255, 0.5);
    padding-right: 15px;
}

.item--active {
    opacity: 1;
    transform: translateY(0);
    filter: blur(0px)
}

.item--active:before {
    top: 50%;
    transition: 0.3s all 0.2s;
    opacity: 1;
}

.item--active .content-title {
    margin: -50px 0 20px 0;
}

.img {
    max-width: 100%;
    box-shadow: 0 10px 15px rgba(0, 0, 0, 0.4);
}

.imga {
    max-width: 100%;
}

.imgb {
    max-width: 100%;
    right: 80%;
}

.subtitle {
    color: rgba(255, 255, 255, 0.5);
    font-size: 16px;
    letter-spacing: 5px;
    margin: 10px 0 0 0;
    font-weight: normal;
}



@media only screen and (max-width: 767px) {
    .item {
        align-self: baseline !important;
        width: 100%;
        padding: 0 30px 150px 80px;
    }

    .item:before {
        left: 10px !important;
        padding: 0 !important;
        top: 50px;
        text-align: center !important;
        width: 60px;
        border: none !important;
    }

    .item:last-child {
        padding-bottom: 40px;
    }
}

@media only screen and (max-width:767px) {
    .timeline:before {
        left: 40px;
    }
}

.welcome-text {
    font-size: 2rem;
    /* 调整文字大小 */
    background: linear-gradient(45deg, #fff, #e9ec15);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    /* 白色字体 */
    text-align: center;
    /* 居中对齐 */
    margin-top: 20px;
    /* 调整与logo之间的距离 */
    letter-spacing: 3px;
    /* 增加字间距 */
    font-weight: bold;
    /* 字体加粗 */
    text-shadow: 2px 2px 8px rgba(0, 0, 0, 0.5);
    /* 增加阴影效果 */

}
.promotion-video{
    display:flex;
    width:100%;
    height: auto;
    top:0px;
    justify-content: center;
    align-items: center;
    background: url('https://static.igem.wiki/teams/5730/wiki/s7.webp') no-repeat center center/cover;
    bottom: 1000px;
    position: relative;
}
/* From Uiverse.io by Cornerstone-04 */ 
.box {
    width: 140px;
    height: auto;
    transition: .5s linear;
    position: relative;
    display: block;
    overflow: hidden;
    padding: 15px;
    text-align: center;
    margin: 0 5px;
    background: transparent;
    text-transform: uppercase;
    font-weight: 900;
    left:50px;
  }
  
  .box:before {
    position: absolute;
    content: '';
    left: 0;
    bottom: 0;
    height: 4px;
    width: 100%;
    border-bottom: 4px solid transparent;
    border-left: 4px solid transparent;
    box-sizing: border-box;
    transform: translateX(100%);
  }
  
  .box:after {
    position: absolute;
    content: '';
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    border-top: 4px solid transparent;
    border-right: 4px solid transparent;
    box-sizing: border-box;
    transform: translateX(-100%);
  }
  
  .box:hover {
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.5);
  }
  
  .box:hover:before {
    border-color: #190fd2;
    height: 100%;
    transform: translateX(0);
    transition: .3s transform linear, .3s height linear .3s;
  }
  
  .box:hover:after {
    border-color: #190fd2;
    height: 100%;
    transform: translateX(0);
    transition: .3s transform linear, .3s height linear .5s;
  }
  
  .button {

    color: black;
    text-decoration: none;
    cursor: pointer;
    outline: none;
    border: none;
    background: transparent;
    display:block;
  }
.button-set{
    float:left;
    height:auto;
    width:200px;
    line-height: 50px;
}
.box a {
    text-decoration: none;
    color:#262626;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}