.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1100;
  background: var(--color-header-bg);
  backdrop-filter: blur(40px);
  -webkit-backdrop-filter: blur(40px);
  display: flex;
  align-items: center;
  transition: box-shadow var(--transition);
}

.header.scrolled {
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
}

.header-nav {
  flex: 1;
  width: 100%;
  height: var(--header-height);
  display: flex;
  align-items: center;
}

.nav-content {
  margin: 0 auto;
  padding: 0 clamp(16px, 4vw, 80px);
  width: 100%;
  max-width: var(--max-content);
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: clamp(16px, 3vw, 40px);
  box-sizing: border-box;
}

.nav-logo {
  grid-column: 1;
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  flex-shrink: 0;
  transition: transform var(--transition);
}

.nav-logo:hover {
  transform: translateY(-1px);
}

.logo-icon {
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.logo-icon img {
  width: 100%;
  height: 100%;
}

.logo-text {
  font-family: var(--font-display);
  font-size: 16px;
  font-weight: 700;
  color: var(--color-text);
  white-space: nowrap;
}

.nav-menu {
  grid-column: 2;
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  align-items: center;
  width: 100%;
  min-width: 0;
  margin: 0;
  padding: 0 clamp(8px, 2vw, 32px);
  list-style: none;
  gap: 0;
}

.nav-menu li {
  display: flex;
  justify-content: center;
  min-width: 0;
}

.nav-menu .nav-link {
  --nav-link-lh: 1.5;
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 8px clamp(4px, 1vw, 12px);
  font-family: var(--font-display);
  font-size: 16px;
  font-weight: 700;
  line-height: var(--nav-link-lh);
  height: calc(1em * var(--nav-link-lh) + 16px);
  overflow: hidden;
  white-space: nowrap;
  border-radius: var(--radius-sm);
}

/* 过程呈水波弧线；100% 各字统一 -50%，最终文字水平对齐 */
@keyframes nav-char-wave-in {
  0% {
    transform: translateY(0);
  }
  38% {
    transform: translateY(calc(-72% + var(--arc, 0em)));
  }
  62% {
    transform: translateY(calc(-38% + var(--arc, 0em)));
  }
  100% {
    transform: translateY(-50%);
  }
}

.nav-link__label {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.nav-link__wave {
  display: inline-flex;
  align-items: flex-end;
  gap: 0.04em;
}

.nav-link__char {
  display: inline-block;
  overflow: hidden;
  height: calc(1em * var(--nav-link-lh));
  line-height: var(--nav-link-lh);
  vertical-align: bottom;
}

.nav-link__char-track {
  display: flex;
  flex-direction: column;
  transform: translateY(0);
  will-change: transform;
}

.nav-menu .nav-link:hover .nav-link__char-track,
.nav-menu .nav-link:focus-visible .nav-link__char-track {
  animation: nav-char-wave-in 500ms cubic-bezier(0.33, 1, 0.45, 1) forwards;
  animation-delay: var(--delay-in, 0ms);
}

.nav-menu .nav-link:not(:hover):not(:focus-visible) .nav-link__char-track {
  animation: none;
  transform: translateY(0);
  transition: transform 500ms cubic-bezier(0.45, 0, 0.55, 1);
  transition-delay: var(--delay-out, 0ms);
}

.nav-link__char-line {
  display: block;
  height: calc(1em * var(--nav-link-lh));
  line-height: var(--nav-link-lh);
  flex-shrink: 0;
  color: var(--color-text);
}

.nav-link__char-line--alt {
  color: var(--color-primary);
}

.nav-menu .nav-link::after {
  content: "";
  position: absolute;
  left: clamp(4px, 1vw, 12px);
  right: clamp(4px, 1vw, 12px);
  bottom: 6px;
  height: 2px;
  background: var(--color-primary);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 500ms cubic-bezier(0.22, 1, 0.36, 1);
}

.nav-menu .nav-link:hover::after,
.nav-menu .nav-link:focus-visible::after {
  transform: scaleX(1);
}

@media (prefers-reduced-motion: reduce) {
  .nav-link__char-track {
    animation: none !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0ms !important;
  }

  .nav-menu .nav-link:hover .nav-link__char-track,
  .nav-menu .nav-link:focus-visible .nav-link__char-track {
    transform: translateY(-50%);
  }

  .nav-menu .nav-link:hover .nav-link__char-line,
  .nav-menu .nav-link:focus-visible .nav-link__char-line {
    color: var(--color-primary);
  }

  .nav-menu .nav-link::after {
    transition-duration: 0.01ms;
  }

  .nav-menu .nav-link:hover::after,
  .nav-menu .nav-link:focus-visible::after {
    transform: scaleX(1);
  }
}

.nav-actions {
  grid-column: 3;
  display: flex;
  align-items: center;
  gap: 16px;
  flex-shrink: 0;
  justify-self: end;
}

.btn {
  padding: 8px 20px;
  border-radius: 20px;
  font-family: var(--font-display);
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  border: none;
  transition: all var(--transition);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 90px;
}

.btn-login {
  background: #000;
  color: #fff;
}

.btn-login:hover {
  background: #333;
  transform: translateY(-1px);
}

.btn-download {
  background: #fff;
  color: #333;
}

.btn-download:hover {
  background: #f5f5f5;
  transform: translateY(-1px);
}

.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 32px;
  height: 32px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  border-radius: 4px;
}

.hamburger-line {
  width: 20px;
  height: 2px;
  background: var(--color-text-secondary);
  margin: 2px 0;
  transition: all var(--transition);
  border-radius: 1px;
}

.mobile-menu-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
  z-index: 9999;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.mobile-menu-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.mobile-menu {
  position: fixed;
  top: 0;
  right: 0;
  width: 320px;
  max-width: 100%;
  height: 100dvh;
  background: rgba(255, 255, 255, 0.97);
  backdrop-filter: blur(20px);
  z-index: 10000;
  transform: translateX(100%);
  transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}

.mobile-menu.open {
  transform: translateX(0);
}

.mobile-menu-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  border-bottom: 1px solid rgba(226, 232, 240, 0.6);
  background: #000;
}

.mobile-menu-header .logo-text {
  color: #fff;
  font-size: 14px;
}

.mobile-menu-close {
  width: 32px;
  height: 32px;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-text-secondary);
  font-size: 24px;
  line-height: 1;
  border-radius: 4px;
}

.mobile-menu-close:hover {
  color: var(--color-primary);
}

.mobile-nav-menu {
  flex: 1;
  padding: 20px 0;
}

.mobile-nav-link {
  display: block;
  padding: 16px 24px;
  color: var(--color-text-secondary);
  font-size: 16px;
  font-weight: 500;
  border-bottom: 1px solid rgba(226, 232, 240, 0.3);
  transition: all var(--transition);
}

.mobile-nav-link:hover {
  background: rgba(40, 184, 148, 0.05);
  color: var(--color-primary);
}

.mobile-actions {
  padding: 20px 24px;
  border-top: 1px solid rgba(226, 232, 240, 0.6);
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.mobile-actions .btn {
  width: 100%;
  height: 44px;
}

@media (min-width: 1780px) {
  .nav-content {
    padding-left: 80px;
    padding-right: 80px;
  }
}

@media (max-width: 1200px) {
  .nav-menu,
  .nav-actions {
    display: none;
  }

  .mobile-menu-toggle {
    display: flex;
    grid-column: 2;
    justify-self: end;
  }

  .nav-content {
    grid-template-columns: 1fr auto;
    padding: 0 40px;
    gap: 20px;
  }

  .nav-logo {
    grid-column: 1;
  }
}

@media (max-width: 768px) {
  .nav-content {
    padding: 0 24px;
  }

  .logo-text {
    font-size: 14px;
  }
}

@media (max-width: 480px) {
  .header-nav {
    height: 56px;
  }

  .nav-content {
    padding: 0 16px;
  }

  .mobile-menu {
    width: 100%;
  }
}