/* ========== 顶部导航栏 ========== */
.top-nav {
  width: 100%;
  padding: 4vh 5vw 2vh;
  display: flex;
  justify-content: center;
  /* 避免被右上角固定元素遮挡 */
  padding-right: calc(5vw + 0px)/*预留右侧用户区域宽度 */
}

.nav-links {
  display: flex;
  gap: clamp(1.5rem, 4vw, 3rem);
}

.nav-links a {
  text-decoration: none;
  color: rgba(255, 255, 255, 0.9);
  font-size: clamp(0.9rem, 1.2vw, 1.1rem);
  font-weight: 400;
  text-shadow: 0 1px 3px rgba(0,0,0,0.15);
  padding: 0.3em 0;
  position: relative;
}

.nav-links a:hover {
  color: #fff;
  text-shadow: 0 0 8px rgba(255,255,255,0.6);
}

/* 下拉菜单 */
.dropdown {
  position: relative;        
  display: inline-flex;      
  align-items: center;       
}
.dropbtn {
  cursor: pointer;
  color: rgba(255, 255, 255, 0.9);
  font-size: clamp(0.9rem, 1.2vw, 1.1rem);
  text-shadow: 0 1px 3px rgba(0,0,0,0.15);
  padding: 0.3em 0;
}
.dropdown-content {
  display: none;
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(12px);
  border-radius: 12px;
  min-width: 140px;
  box-shadow: 0 8px 20px rgba(0,0,0,0.15);
  z-index: 1001;
  padding: 0.4em 0;
}
.dropdown-content a {
  display: block;
  padding: 0.6em 1.2em;
  color: #fff;
  text-decoration: none;
  font-size: 0.9rem;
  white-space: nowrap;
}
.dropdown-content a:hover {
  background: rgba(255,255,255,0.3);
}
.dropdown:hover .dropdown-content {
  display: block;
}

/* ========== 中间卡片区域 ========== */
.main-content {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 5vh 8vw;
}

.placeholder-card {
  width: 100%;
  max-width: 800px;
  height: 100%;
  min-height: 260px;
  background: rgba(255, 255, 255, 0.12);
  backdrop-filter: blur(16px);
  border-radius: 24px;
  border: 1px solid rgba(255, 255, 255, 0.25);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.15), inset 0 1px 1px rgba(255,255,255,0.3);
  display: flex;
  align-items: center;
  justify-content: center;
}

.placeholder-text {
  font-size: clamp(1rem, 2.5vw, 1.8rem);
  color: rgba(255, 255, 255, 0.55);
  font-weight: 300;
  letter-spacing: 0.05em;
  user-select: none;
}

/* ========== 底部友情链接 ========== */
.footer-links {
  width: 100%;
  padding: 2vh 5vw;
  display: flex;
  justify-content: center;
  gap: 2rem;
}

.footer-links a {
  text-decoration: underline;
  text-underline-offset: 3px;
  color: rgba(255, 255, 255, 0.65);
  font-size: clamp(0.65rem, 0.9vw, 0.8rem);
  transition: color 0.2s;
}

.footer-links a:hover {
  color: #fff;
}

/* ========== 右上角固定用户区域 ========== */
.user-area {
  position: fixed;
  top: 0.5rem;
  right: 0.5rem;
  z-index: 1000;
  display: flex;
  flex-direction: column;      /* 改为纵向排列 */
  align-items: center;
  gap: 0.5rem;                 /* 元素间垂直间距 */
  backdrop-filter: blur(8px);
  padding: 0.8rem 0.9rem;
  border-radius: 40px;
}

.avatar {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background-image: url('images/avatar.png');  
  background-size: cover;
  background-position: center;
  border: 2px solid rgba(255, 255, 255, 0.6);
  flex-shrink: 0;
}

.username {
  font-size: 0.9rem;
  font-weight: 500;
  text-shadow: 0 1px 4px rgba(0,0,0,0.2);
  white-space: nowrap;
}