*{
    padding: 0%;
    margin: 0%;
}
   
body {
    margin: 0;
    padding: 0;
    background: #212121;
}

header{
    display: flex;
    flex-direction: column;   
    border: black;
}

header ul{
    position: absolute;
    right: 5vw;
    top: 0;
    line-height: 100px;
}
header li{
    display: inline;
    margin-right: 4vw;
}

h1{
    font-size:50px;
    margin: 15px 60px;
}

.nav_button {
    margin: -40px;
    margin-left: 5px;
    height: auto;
    background: transparent;
    padding: 0;
    border: none;
    cursor: pointer;
    --border-right: 6px;
    --text-stroke-color: rgba(255, 255, 255);
    --animation-color: #44ffc7;
    --fs-size: 2em;
    letter-spacing: 3px;
    text-decoration: none;
    font-size: var(--fs-size);
    font-family: "Arial";
    position: relative;
    color: transparent;
    -webkit-text-stroke: 1px var(--text-stroke-color);
    outline: none;
}

.hovertext {
    position: absolute;
    box-sizing: border-box;
    content: attr(data-text);
    color: var(--animation-color);
    width: 0%;
    inset: 0;
    border-right: var(--border-right) solid var(--animation-color);
    overflow: hidden;
    transition: 0.5s;
    -webkit-text-stroke: 1px var(--animation-color);
}

.nav_button:hover .hovertext {
    width: 100%;
    filter: drop-shadow(0 0 20px var(--animation-color))
}

.nav_button_s {
    margin: -40px;
    margin-left: 5px;
    height: auto;
    background: transparent;
    padding: 0;
    border: none;
    cursor: pointer;
    --border-right: 6px;
    --text-stroke-color: rgba(255, 255, 255);
    --animation-color: #44ffc7;
    --fs-size: 2em;
    letter-spacing: 3px;
    text-decoration: none;
    font-size: var(--fs-size);
    font-family: "Arial";
    position: relative;
    color: transparent;
    -webkit-text-stroke: 1px var(--text-stroke-color);
    outline: none;
}

.hovertext {
    position: absolute;
    box-sizing: border-box;
    content: attr(data-text);
    color: var(--animation-color);
    width: 0%;
    inset: 0;
    border-right: var(--border-right) solid var(--animation-color);
    overflow: hidden;
    transition: 0.5s;
    -webkit-text-stroke: 1px var(--animation-color);
}

.nav_button_s .hovertext {
    width: 100%;
    filter: drop-shadow(0 0 20px var(--animation-color))
}


a{
    text-decoration: none;
}

nav {
    border-bottom: 1px solid white;
  }

main{
    font-size: 20px;
    display: flex;
    flex-direction: column;
}

h2{
    color: aliceblue; 
    font-size: 40px;
    margin: 10px 100px;
}

h3{
    color: aliceblue; 
    margin: 10px 100px;
}

p{
    color: aliceblue;  
    margin: 10px 100px;
    line-height: 1.5;
    font-family: 'Times New Roman', Times, serif;
    border-bottom: 0.5px solid white;
}

#backToTopBtn {
    display: none; /* 默认隐藏 */
    position: fixed; /* 固定位置 */
    bottom: 40px; /* 距离底部20px */
    right: 50px; /* 距离右边30px */
    z-index: 99; /* 确保按钮在其他内容之上 */
    padding: 25px 25px;
    background-color: rgba(55, 49, 49, 0.794);
    border-radius: 10px;
    border: none;
    background-image:url(../images/vertical_align_top_24dp_E3E3E3_FILL0_wght400_GRAD0_opsz24.png) ;
    background-size: 50px 50px;
    background-repeat: none;
    outline: none;
  }
  
  #backToTopBtn:hover{
    cursor: pointer;
    background-color: #44ffc7;
}

  .aspect-ratio {
    position: relative;
    width: 85%;
    height: 0;
    padding-bottom: 50%;
    margin: 10px 100px;
}

.aspect-ratio iframe {
    display: flex;
    justify-content: center;
    position: absolute;
    width: 100%;
    height: 100%;
    left: 0;
    top: 0;
}