* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

html {
  scroll-behavior: smooth;
}

/* 主背景改为黑色，文字默认白色（视频背景下此部分可弱化） */
body {
  background-color: #000;
  color: #fff;
}

/* 1. 导航栏：透明背景 + 缩减高度 + 白色文字 */
#navbar {
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 50;
  transition: all 0.3s ease;
  padding: 0.5rem 2rem; /* 减少内边距，降低高度 */
  background-color: transparent; /* 初始透明 */
  box-shadow: none; /* 移除默认阴影 */
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

/* Logo 图标容器：透明背景 */
.logo-icon {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 0.75rem;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
}

/* Logo 文字：白色 */
.logo-text {
  font-size: 1.25rem;
  font-weight: 700;
  color: #fff;
}

/* 桌面导航：默认隐藏（小屏），文字白色 + hover科技蓝 */
.desktop-nav {
  display: none;
  gap: 2rem;
}

.desktop-nav a {
  text-decoration: none;
  color: #fff;
  transition: color 0.2s ease;
}

.desktop-nav a:hover {
  color: #165DFF; /* hover 科技蓝 */
}

/* 登录/注册按钮组 */
.auth-buttons {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* 登录按钮：白色文字 */
.login-btn {
  display: none;
  color: #fff;
  text-decoration: none;
  padding: 0.5rem 1rem;
  transition: color 0.2s ease;
}

.login-btn:hover {
  color: #165DFF;
}

/* 注册按钮：科技蓝风格保持 */
.register-btn {
  background-color: #165DFF;
  color: #fff;
  text-decoration: none;
  padding: 0.5rem 1.25rem;
  border-radius: 0.5rem;
  transition: all 0.3s ease;
  box-shadow: 0 4px 12px rgba(22, 93, 255, 0.2);
}

.register-btn:hover {
  background-color: #0E4BD8;
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(22, 93, 255, 0.3);
}

/* 移动端菜单按钮：白色图标 */
.menu-toggle {
  display: block;
  color: #fff;
  font-size: 1.5rem;
  border: none;
  background: transparent;
  cursor: pointer;
}

/* 移动端菜单：半透明黑背景 + 白色文字 */
.mobile-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  width: 100%;
  background-color: rgba(0, 0, 0, 0.8); /* 半透明黑增强可读性 */
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  padding: 1rem 2rem;
}

.mobile-menu a {
  display: block;
  text-decoration: none;
  color: #fff;
  padding: 0.75rem 0;
  border-radius: 0.5rem;
  transition: background-color 0.2s ease;
}

.mobile-menu a:hover {
  background-color: rgba(255, 255, 255, 0.1);
}

/* 2. 背景视频：铺满全屏 */
.hero-video {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover; /* 保持比例并铺满 */
  z-index: -1; /* 置于内容下层 */
}

/* 英雄区域遮罩：弱化视频亮度，增强文字可读性 */
.hero-overlay {
  position: absolute;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.3); /* 半透明遮罩，可调整透明度 */
}

.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem;
  position: relative; /* 为视频和遮罩提供定位基准 */
}

.hero-content {
  max-width: 800px;
  text-align: center;
  color: #fff;
  position: relative;
  z-index: 10;
}

.hero-title {
  font-size: clamp(1.8rem, 5vw, 3rem);
  font-weight: 700;
  margin-bottom: 1.5rem;
  line-height: 1.2;
}

/* 渐变文字（科技感强调） */
.gradient-text {
  background: linear-gradient(90deg, #165DFF, #36CBCB);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-desc {
  font-size: clamp(1rem, 2vw, 1.2rem);
  color: rgba(255, 255, 255, 0.8);
  margin-bottom: 3rem;
  max-width: 500px;
  margin-left: auto;
  margin-right: auto;
}

/* 行动按钮组 */
.action-buttons {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  align-items: center;
}

/* 进入首页按钮：科技蓝+白色文字 */
.enter-btn {
  background-color: #165DFF;
  color: #fff;
  text-decoration: none;
  padding: 1rem 2rem;
  border-radius: 0.5rem;
  font-weight: 600;
  font-size: 1.1rem;
  transition: all 0.3s ease;
  box-shadow: 0 4px 12px rgba(22, 93, 255, 0.2);
}

.enter-btn:hover {
  background-color: #0E4BD8;
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(22, 93, 255, 0.3);
}

/* 登录/注册链接：透明边框+白色文字 */
.auth-link {
  background-color: transparent;
  color: #fff;
  text-decoration: none;
  padding: 1rem 2rem;
  border: 2px solid #fff;
  border-radius: 0.5rem;
  font-weight: 600;
  font-size: 1.1rem;
  transition: all 0.3s ease;
}

.auth-link:hover {
  background-color: rgba(255, 255, 255, 0.1);
}

/* 3. 导航栏滚动效果：滚动后半透明黑背景 */
.nav-scrolled {
  background-color: rgba(0, 0, 0, 0.8); /* 半透明黑 */
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2); /* 可选：轻微阴影 */
}

.nav-scrolled .logo-text,
.nav-scrolled .desktop-nav a,
.nav-scrolled .login-btn,
.nav-scrolled .menu-toggle {
  color: #fff; /* 确保滚动后文字仍为白色 */
}

/* 4. 页脚：透明背景+优化文字可读性（替换原有代码） */
.footer {
  position: absolute;
  bottom: 0;
  width: 100%;
  padding: 1rem 0;
  text-align: center;
  background-color: transparent !important; /* 核心：改为透明背景，!important确保覆盖原有黑色 */
  text-shadow: 0 0 2px rgba(0, 0, 0, 0.6); /* 新增文字阴影，在视频背景上更清晰 */
}

.footer .container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

.copyright a {
  color: rgba(255, 255, 255, 0.8); /* 微调文字透明度，比原来更亮一点 */
  font-size: 0.9rem;
  text-decoration: none;
}

.copyright a:hover {
  color: white;
  text-decoration: underline;
}

/* 响应式：大屏显示桌面导航 */
@media (min-width: 768px) {
  .desktop-nav {
    display: flex;
  }

  .menu-toggle {
    display: none;
  }

  .login-btn {
    display: block;
  }

  .action-buttons {
    flex-direction: row;
    justify-content: center;
    gap: 2rem;
  }
}