#topnav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(0,0,0,0.9); backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255,255,255,0.06);
}
#topnav .nav-container {
  max-width: 1200px; margin: 0 auto; padding: 0 24px;
  display: flex; align-items: center; justify-content: space-between;
  height: 60px;
}
#topnav .navlogo a { display: flex; align-items: center; }
#topnav .navlogo img { height: 32px; }
#topnav .nav-menu {
  display: flex; align-items: center; gap: 4px;
}
#topnav .nav-menu a {
  color: rgba(255,255,255,0.7);
  font-size: 0.82em; font-weight: 600;
  padding: 8px 16px; border-radius: 6px;
  transition: color 0.2s, background 0.2s;
  letter-spacing: 0.5px;
  font-family: "ヒラギノ角ゴ Pro W3", "Hiragino Kaku Gothic Pro", "メイリオ", Meiryo, sans-serif;
}
#topnav .nav-menu a:hover {
  color: #fff;
  background: rgba(255,255,255,0.08);
}
#topnav .nav-menu a.nav-active {
  color: #de3b04;
  background: rgba(222,59,4,0.1);
}
#topnav .nav-menu a[target="_blank"]::after {
  content: '↗'; font-size: 0.75em; margin-left: 3px;
  opacity: 0.5;
}

/* Hamburger */
#topnav .nav-toggle {
  display: none;
  background: none; border: none; cursor: pointer;
  padding: 8px; flex-direction: column; gap: 5px;
}
#topnav .nav-toggle span {
  display: block; width: 22px; height: 2px;
  background: #fff; border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}

@media (max-width: 768px) {
  #topnav .nav-container { height: 52px; }
  #topnav .navlogo img { height: 28px; }
  #topnav .nav-toggle { display: flex; }
  #topnav .nav-menu {
    display: none; position: absolute;
    top: 52px; left: 0; right: 0;
    background: rgba(0,0,0,0.95);
    flex-direction: column; padding: 8px 16px 16px;
    gap: 0; border-top: 1px solid rgba(255,255,255,0.08);
  }
  #topnav .nav-container.open .nav-menu { display: flex; }
  #topnav .nav-menu a {
    padding: 14px 16px; border-radius: 0;
    border-bottom: 1px solid rgba(255,255,255,0.05);
    font-size: 0.9em; width: 100%;
  }
  #topnav .nav-container.open .nav-toggle span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }
  #topnav .nav-container.open .nav-toggle span:nth-child(2) { opacity: 0; }
  #topnav .nav-container.open .nav-toggle span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
  }
}