/* reset & base */
*{ box-sizing:border-box; }
body{
  margin:0;
  font-family: "Zalando Sans Expanded", Arial, sans-serif;
  color:#111;
  background:#000;
}

.fallback-header {
    display: none;
}

.visually-hidden, .intro-seo {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0); 
    clip-path: inset(50%);
    white-space: nowrap;
    border: 0;
}

/* layout helpers */
.container{
  width:min(1200px, 92%);
  margin:0 auto;
}

/* header/nav */
.site-header{
  position:relative; /* 默认占据文档流空间 */
  top:0; left:0; right:0;
  z-index:99;
  background:rgba(0,0,0,.45);
  backdrop-filter: blur(6px);
  transition: all 0.3s ease; /* 平滑过渡 */
}

/* 滚动后变为固定定位 */
.site-header.scrolled{
  position:fixed;
  top:0;
  box-shadow: 0 2px 10px rgba(0,0,0,0.3); /* 添加阴影增强层次感 */
}
.navbar{
  display:flex;
  align-items:center;
  justify-content:space-between;
  padding:8px 0; /* 减少padding从12px到8px */
}
.brand{
  display:flex; align-items:center; gap:10px;
  color:#fff; text-decoration:none; font-weight:700;
  letter-spacing:.06em;
}
.brand img{ height:34px; }

.nav{
  display:flex; gap:20px; align-items:center;
}
.nav a{
  color:#fff; text-decoration:none; font-size:15px;
  opacity:.9;
  padding:6px 2px;
  border-bottom:2px solid transparent;
}
.nav a.active, .nav a:hover{
  opacity:1;
  border-bottom-color:#7cc3ff;
}

/* mobile menu */
.nav-toggle{
  display:none;
  background:none; border:0; color:#fff; font-size:24px;
  cursor: pointer;
}
@media (max-width: 900px){
  /* 防止移动端水平滚动 - 修复抽屉菜单导致的水平滚动条 */
  body, html {
    overflow-x: hidden !important;
    max-width: 100vw;
  }

  .nav-toggle{ display:block; }
  .nav{
    position:fixed;
    top:50px; /* 紧贴页头底部，无gap */
    right:0;
    width: 70%; /* 抽屉宽度 */
    height: calc(100vh - 50px); /* 占满剩余高度 */

    display:flex;
    flex-direction:column;
    gap:12px;

    background:rgba(0,0,0,0.85); /* 半透明黑色 */
    padding:20px 0;

    box-shadow: -4px 0 15px rgba(0,0,0,0.3); /* 左侧阴影效果 */

    /* 滑入动画：默认隐藏在右侧外 */
    transform: translateX(100%);
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);

    z-index: 98; /* 确保在页头下方 */
  }
  .nav.open{
    transform: translateX(0); /* 滑入可见 */
  }
}

/* footer */
.site-footer{
  background:#050505;
  color:#bbb;
  padding:10px 0; /* 减少上下padding，从28px改为10px */
  font-size:13px; /* 稍微减小字体 */
}
.site-footer .foot-row{
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:12px;
  flex-wrap:wrap;
  /* 不使用container的宽度限制，使用padding控制边距 */
  width:100%;
  max-width:none !important; /* 覆盖container的max-width */
  padding-left:clamp(20px, 4%, 60px); /* 左侧padding */
  padding-right:clamp(20px, 4%, 60px); /* 右侧padding */
  margin:0;
}
.site-footer a{ color:#bbb; }

/* Footer右侧文字块 */
.site-footer .site-footer-footnote {
  width: 65%; /* 固定宽度65%，不随屏幕变化 */
  max-width: 800px; /* 最大宽度限制 */
  text-align: right;
  line-height: 1.3;
  font-size: clamp(8px, 0.7vw, 10px); /* 恢复原来的字体大小 */
}

/* 移动端优化 */
@media (max-width: 768px) {
  .site-footer .foot-row {
    padding-left: 15px;
    padding-right: 15px;
    gap: 10px;
    align-items: flex-start; /* 顶部对齐 */
  }

  .site-footer .site-footer-footnote {
    width: auto; /* 移动端自动宽度 */
    flex: 1; /* 占据剩余空间，但不超出 */
    max-width: calc(100% - 120px); /* 留出左侧文字的空间 */
    text-align: right; /* 保持右对齐 */
    font-size: 9px; /* 移动端稍小 */
    line-height: 1.25;
  }
}

/* pdf background section helper */
.pdf-section{
  position:relative;
  width:100%;
  aspect-ratio: 2048 / 1149; /* 默认大屏按页比例复刻 */
  overflow:hidden;
}
.pdf-section .bg{
  position:absolute; inset:0;
  width:100%; height:100%;
  object-fit:cover;
}
.pdf-section .overlay{
  position:absolute; inset:0;
}

/* small-screen mode: let height grow */
@media (max-width: 900px){
  .pdf-section{
    aspect-ratio:auto;
    min-height:100vh;
    overflow:visible;
  }
  .pdf-section .overlay{
    position:relative;
    display:flex;
    flex-direction:column;
    align-items:center;
  }
}

/* buttons */
.btn{
  display:inline-block;
  padding:10px 16px;
  border-radius:999px;
  background:#7cc3ff;
  color:#000;
  font-weight:600;
  text-decoration:none;
}
.btn.ghost{
  background:transparent; color:#fff; border:1px solid rgba(255,255,255,.6);
}

/* ===== Mobile Navigation Buttons (Mobile Only) ===== */
/* Hidden by default on desktop */
.mobile-nav-enter,
.mobile-nav-arrows {
  display: none;
}

/* Mobile version only */
@media (max-width: 900px) {
  /* Enter button for Home page */
  .mobile-nav-enter {
    display: block;
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    bottom: 25vh; /* Position below title */
    z-index: 10;
  }

  .mobile-nav-enter a {
    display: inline-block;
    padding: 12px 32px;
    font-size: 16px;
    font-weight: 500;
    color: #fff;
    text-decoration: none;
    background: rgba(255, 255, 255, 0.08);
    border: 1.5px solid rgba(70, 118, 116, 0.6);
    border-radius: 999px;
    backdrop-filter: blur(3px);
    transition: all 0.3s ease;
    letter-spacing: 0.5px;
  }

  .mobile-nav-enter a:hover {
    background: rgba(255, 255, 255, 0.15);
    border-color: rgba(70, 118, 116, 0.8);
    transform: scale(1.05);
  }

  /* Arrow navigation container */
  .mobile-nav-arrows {
    display: flex;
    justify-content: space-between;
    align-items: center;
    position:absolute;
    bottom: 20px;
    left: 20px;
    right: 20px;
    z-index: 10;
    pointer-events: none; /* Allow clicks through container */
  }

  .mobile-nav-arrows a {
    pointer-events: auto; /* Enable clicks on buttons */
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background: rgba(255, 255, 255, 0.08);
    border: 1.5px solid rgba(70, 118, 116, 0.5);
    border-radius: 50%;
    backdrop-filter: blur(3px);
    transition: all 0.3s ease;
    text-decoration: none;
  }

  .mobile-nav-arrows a:hover {
    background: rgba(255, 255, 255, 0.15);
    border-color: rgba(70, 118, 116, 0.75);
    transform: scale(1.1);
  }

  /* Arrow SVG icons */
  .mobile-nav-arrows a svg {
    width: 24px;
    height: 24px;
    fill: #4676A6;
    opacity: 0.9;
  }

  .mobile-nav-arrows a:hover svg {
    opacity: 1;
  }

  /* Spacer for single arrow (when only left or right is needed) */
  .mobile-nav-spacer {
    width: 50px;
    height: 50px;
  }
}