* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
body {
  color: #333;
  font-family: Microsoft YaHei, PingFang SC, Helvetica Neue, Arial, sans-serif;
  line-height: 1.6;
}
.container {
  margin: 0 auto;
  max-width: 1200px;
  padding: 0 20px;
}
.modern-header {
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  position: relative;
  z-index: 1000;
}
.header-top {
  border-bottom: 3px solid #f59e0b;
  color: #000;
  padding: 20px 0;
}
.header-brand {
  align-items: center;
  display: flex;
  gap: 20px;
}
.logo-wrapper {
  /* background: crimson; */
  border-radius: 50%;
  flex-shrink: 0;
}
.brand-logo {
  border-radius: 50%;
  height: 100px;
  width: 100px;
}
.brand-info {
  color: #000;
  flex: 1;
}
.brand-title {
  color: #000;
  font-size: 1.8rem;
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 8px;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}
.brand-subtitle {
  font-size: 1rem;
  font-weight: 400;
  line-height: 1.4;
  margin-bottom: 15px;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
}
.brand-meta {
  align-items: center;
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
}
.conference-date,
.conference-location {
  align-items: center;
  backdrop-filter: blur(10px);
  border-radius: 20px;
  display: flex;
  font-size: 0.9rem;
  font-weight: 500;
  gap: 8px;
  padding: 8px 15px;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
}
.conference-date i,
.conference-location i {
  color: #f59e0b;
  filter: drop-shadow(0 1px 2px rgba(0, 0, 0, 0.3));
}
.header-nav {
  backdrop-filter: blur(10px);
  position: sticky;
  top: 0;
  transition: all 0.3s ease;
  z-index: 999;
}
.nav-scrolled {
  left: 0;
  position: fixed;
  right: 0;
  top: 0;
}
.modern-header.scrolled .header-top {
  opacity: 0;
  pointer-events: none;
  transform: translateY(-100%);
  visibility: hidden;
}
.header-top {
  opacity: 1;
  transform: translateY(0);
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  visibility: visible;
}
.nav-container {
  justify-content: space-between;
  padding: 12px 0;
}
.nav-container,
.nav-menu {
  align-items: center;
  display: flex;
}
.nav-menu {
  gap: 0;
  list-style: none;
}
.nav-item {
  position: relative;
}
.nav-link {
  align-items: center;
  border-radius: 25px;
  color: #000;
  display: flex;
  font-weight: 500;
  gap: 6px;
  margin: 0 2px;
  padding: 12px 20px;
  text-decoration: none;
  transition: all 0.3s ease;
}
.nav-link:hover {
  background: #f59e0b;
  box-shadow: 0 4px 15px rgba(245, 158, 11, 0.4);
  color: #000;
  transform: translateY(-2px);
}
.nav-link i {
  font-size: 0.9rem;
}
.dropdown-menu {
  background: #fff;
  border: 1px solid rgba(0, 0, 0, 0.1);
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
  left: 50%;
  min-width: 200px;
  opacity: 0;
  padding: 10px 0;
  position: absolute;
  top: 100%;
  transform: translateX(-50%);
  transition: all 0.3s ease;
  visibility: hidden;
  z-index: 1000;
}
.nav-item:hover .dropdown-menu {
  opacity: 1;
  overflow: hidden;
  transform: translateX(-50%) translateY(5px);
  visibility: visible;
}
.dropdown-menu li {
  list-style: none;
}
.dropdown-menu a {
  color: #333;
  display: block;
  font-weight: 400;
  padding: 10px 20px;
  text-decoration: none;
  transition: all 0.3s ease;
}
.dropdown-menu a:hover {
  background: #f59e0b;
  color: #000;
}
.nav-actions {
  align-items: center;
  display: flex;
  gap: 15px;
}
.auth-buttons {
  display: flex;
  gap: 8px;
}
.auth-btn {
  align-items: center;
  border-radius: 25px;
  display: flex;
  font-size: 0.9rem;
  font-weight: 500;
  gap: 6px;
  padding: 8px 16px;
  text-decoration: none;
  transition: all 0.3s ease;
}
.login-btn {
  background: hsla(0, 0%, 100%, 0.1);
  border: 1px solid hsla(0, 0%, 100%, 0.3);
  color: #000;
}
.login-btn:hover {
  background: hsla(0, 0%, 100%, 0.2);
  color: #000;
  transform: translateY(-1px);
}
.register-btn {
  background: #f59e0b;
  border: 1px solid #f59e0b;
  color: #000;
}
.register-btn:hover {
  background: #d97706;
  border-color: #d97706;
  transform: translateY(-1px);
}
.mobile-menu-btn {
  background: hsla(0, 0%, 100%, 0.1);
  border: 2px solid hsla(0, 0%, 100%, 0.2);
  border-radius: 8px;
  cursor: pointer;
  display: none;
  flex-direction: column;
  padding: 8px;
  transition: all 0.3s ease;
}
.mobile-menu-btn:hover {
  background: hsla(0, 0%, 100%, 0.2);
  border-color: #f59e0b;
  transform: scale(1.05);
}
.mobile-menu-btn span {
  background: hsla(0, 0%, 100%, 0.9);
  border-radius: 2px;
  height: 3px;
  margin: 3px 0;
  transition: all 0.3s ease;
  width: 25px;
}
.mobile-menu-btn:hover span {
  background: #f59e0b;
}
@media (max-width: 768px) {
  .modern-header {
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
    padding: 0;
  }
  .header-top {
    padding: 15px 0;
  }
  .header-brand {
    align-items: center;
    flex-direction: column;
    gap: 15px;
    text-align: center;
  }
  .brand-logo {
    height: 80px;
    width: 80px;
  }
  .brand-title {
    font-size: 1.3rem;
    padding: 0 10px;
  }
  .brand-subtitle {
    font-size: 0.9rem;
    padding: 0 15px;
  }
  .brand-meta {
    align-items: center;
    flex-direction: column;
    gap: 8px;
  }
  .conference-date,
  .conference-location {
    font-size: 0.85rem;
    padding: 6px 12px;
  }
  .nav-container {
    padding: 8px 15px;
  }
  .nav-menu {
    display: none;
  }
  .mobile-menu-btn {
    display: flex;
  }
  .auth-buttons {
    display: flex;
    gap: 6px;
  }
  .auth-btn {
    font-size: 0.8rem;
    padding: 6px 12px;
  }
}
@media (max-width: 480px) {
  .header-top {
    padding: 12px 0;
  }
  .brand-logo {
    height: 70px;
    width: 70px;
  }
  .brand-title {
    font-size: 1.1rem;
    padding: 0 8px;
  }
  .brand-subtitle {
    font-size: 0.8rem;
    padding: 0 12px;
  }
  .conference-date,
  .conference-location {
    font-size: 0.75rem;
    padding: 4px 10px;
  }
  .auth-btn {
    font-size: 0.75rem;
    padding: 5px 8px;
  }
  .auth-btn span {
    display: none;
  }
  .auth-btn i {
    font-size: 0.9rem;
  }
}
@media (max-width: 768px) and (orientation: landscape) {
  .header-top {
    padding: 10px 0;
  }
  .header-brand {
    align-items: center;
    flex-direction: row;
    gap: 15px;
  }
  .brand-logo {
    height: 60px;
    width: 60px;
  }
  .brand-info {
    flex: 1;
    text-align: left;
  }
  .brand-title {
    font-size: 1.1rem;
    margin-bottom: 4px;
  }
  .brand-subtitle {
    font-size: 0.8rem;
    margin-bottom: 6px;
  }
  .brand-meta {
    flex-direction: row;
    gap: 10px;
    justify-content: flex-start;
  }
  .conference-date,
  .conference-location {
    font-size: 0.7rem;
    padding: 2px 8px;
  }
}
@media (max-width: 768px) {
  .nav-menu-active {
    background: rgba(220, 38, 38, 0.98);
    border-radius: 0 0 10px 10px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
    display: flex;
    flex-direction: column;
    gap: 8px;
    left: 0;
    padding: 15px;
    position: absolute;
    right: 0;
    top: 100%;
    z-index: 1000;
  }
  .nav-menu-active .nav-item {
    width: 100%;
  }
  .nav-menu-active .nav-link {
    background: hsla(0, 0%, 100%, 0.1);
    border: 1px solid hsla(0, 0%, 100%, 0.2);
    border-radius: 8px;
    justify-content: center;
    padding: 12px 15px;
  }
  .nav-menu-active .dropdown-menu {
    background: hsla(0, 0%, 100%, 0.1);
    border-radius: 8px;
    margin-top: 8px;
    opacity: 1;
    position: static;
    transform: none;
    visibility: visible;
  }
}