/* 导航栏 */
.topnav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: var(--bg-nav);
  backdrop-filter: saturate(1.4) blur(12px);
  -webkit-backdrop-filter: saturate(1.4) blur(12px);
  border-bottom: 1px solid var(--hair);
  transition: background 0.2s;
}

.topnav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-3);
  display: flex;
  align-items: center;
  height: var(--nav-height);
  gap: var(--space-3);
}

.topnav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 17px;
  color: var(--ink);
  letter-spacing: -0.01em;
}

.topnav-links {
  display: flex;
  gap: 6px;
  margin-left: auto;
  align-items: center;
}

.topnav-links a {
  font-size: 14px;
  font-weight: 500;
  color: var(--muted);
  padding: 6px 12px;
  border-radius: 6px;
  transition: all 0.15s;
}

.topnav-links a:hover,
.topnav-links a.active {
  color: var(--ink);
  background: var(--subtle);
}

/* 移动端菜单 */
.hamburger {
  display: none;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 8px;
  margin-left: auto;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--ink);
  margin: 5px 0;
  transition: all 0.3s;
}

@media (max-width: 768px) {
  .topnav-links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--paper);
    flex-direction: column;
    gap: 0;
    padding: var(--space-3);
    transform: translateX(100%);
    transition: transform 0.3s;
    border-top: 1px solid var(--hair);
  }

  .topnav-links.active {
    transform: translateX(0);
  }

  .topnav-links a {
    width: 100%;
    padding: var(--space-2);
    text-align: left;
    font-size: 16px;
  }

  .hamburger {
    display: block;
  }

  .hamburger.active span:nth-child(1) {
    transform: rotate(45deg) translate(7px, 7px);
  }

  .hamburger.active span:nth-child(2) {
    opacity: 0;
  }

  .hamburger.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -7px);
  }
}