/* ========== Header / Nav ========== */
.header {
  position: sticky; top: 0; z-index: 1000;
  background: var(--bg-nav);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  transition: background var(--transition-normal), border-color var(--transition-normal);
}
.header-inner {
  max-width: var(--max-width); margin: 0 auto;
  padding: 0 24px; height: 64px;
  display: flex; align-items: center; justify-content: space-between;
  gap: 32px;
}
.logo-area { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.logo-img { width: 38px; height: 38px; border-radius: 10px; flex-shrink: 0; box-shadow: 0 2px 8px rgba(14,165,233,0.3); }
.logo-text { font-size: 20px; font-weight: 700; color: var(--text-primary); letter-spacing: 0.5px; }
.logo-sub { font-size: 11px; color: var(--text-muted); display: block; line-height: 1; margin-top: 1px; }

.nav-links { display: flex; align-items: center; gap: 4px; }
.nav-links a {
  padding: 8px 15px; border-radius: 8px; font-size: 14px; font-weight: 500;
  color: var(--text-secondary); transition: all var(--transition-fast);
  white-space: nowrap;
}
.nav-links a:hover { color: var(--color-accent); background: rgba(14,165,233,0.06); }
.nav-links a.active { color: var(--color-accent); font-weight: 600; }

.nav-actions { display: flex; align-items: center; gap: 8px; flex-shrink: 0; }
.btn-icon {
  width: 36px; height: 36px; border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  color: var(--text-secondary); transition: all var(--transition-fast);
  font-size: 17px;
}
.btn-icon:hover { background: var(--bg-secondary); color: var(--text-primary); }
.btn-join {
  padding: 8px 18px; border-radius: 8px;
  font-size: 13px; font-weight: 600;
  background: linear-gradient(135deg, #0ea5e9, #7c3aed);
  color: #fff; transition: all var(--transition-fast);
  box-shadow: 0 2px 8px rgba(14,165,233,0.25);
  white-space: nowrap;
}
.btn-join:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(14,165,233,0.35);
}

.hamburger { display: none; }

/* ========== Footer ========== */
.footer {
  margin-top: 80px; background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 48px 24px 32px;
  transition: background var(--transition-normal);
}
.footer-inner { max-width: var(--max-width); margin: 0 auto; }
.footer-top { display: flex; gap: 48px; flex-wrap: wrap; margin-bottom: 36px; }
.footer-brand { flex: 1; min-width: 260px; }
.footer-brand .logo-area { margin-bottom: 12px; }
.footer-brand p { font-size: 13px; color: var(--text-secondary); line-height: 1.7; max-width: 360px; }
.footer-links { display: flex; gap: 48px; flex-wrap: wrap; }
.footer-col h4 { font-size: 14px; font-weight: 700; margin-bottom: 14px; }
.footer-col a {
  display: block; font-size: 13px; color: var(--text-muted);
  padding: 4px 0; transition: color var(--transition-fast);
}
.footer-col a:hover { color: var(--color-accent); }
.footer-bottom {
  border-top: 1px solid var(--border-color); padding-top: 20px;
  display: flex; align-items: center; justify-content: space-between;
  flex-wrap: wrap; gap: 12px;
  font-size: 12px; color: var(--text-muted);
}
.footer-bottom-links { display: flex; gap: 16px; flex-wrap: wrap; }
.footer-bottom-links a:hover { color: var(--color-accent); }

/* ========== Footer Beian ========== */
.footer-beian {
  text-align: center; padding-top: 12px;
  font-size: 12px; color: var(--text-muted);
}
.footer-beian a {
  color: var(--text-muted); text-decoration: none; transition: color var(--transition-fast);
}
.footer-beian a:hover { color: var(--color-accent); }

/* ========== Mobile Nav Overlay ========== */
.mobile-nav {
  display: none; position: fixed; inset: 0; z-index: 2000;
  background: rgba(0,0,0,0.5);
}
.mobile-nav.open { display: block; }
.mobile-nav-panel {
  position: fixed; top: 0; right: 0; bottom: 0; width: 280px;
  background: var(--bg-primary); padding: 24px;
  overflow-y: auto;
  box-shadow: -4px 0 20px rgba(0,0,0,0.15);
}
.mobile-nav-panel a {
  display: block; padding: 12px 0; font-size: 15px; font-weight: 500;
  color: var(--text-primary); border-bottom: 1px solid var(--border-color);
}
.mobile-nav-panel .btn-join { margin-top: 16px; text-align: center; display: block; border-radius: 8px; }
.mobile-nav-close { position: absolute; top: 16px; right: 16px; font-size: 22px; }

/* ========== Responsive ========== */
@media (max-width: 991px) {
  .nav-links { display: none; }
  .hamburger { display: flex; }
}
@media (max-width: 767px) {
  .footer-top { flex-direction: column; }
}