.site-header {
  position: fixed;
  top: 1.5rem;
  left: 50%;
  transform: translateX(-50%);
  width: calc(100% - 2rem);
  max-width: 1200px;
  background: rgba(11, 15, 25, 0.75);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 50px;
  z-index: 1000;
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  padding: 0.75rem 2rem;
  box-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
}

.header-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0;
}

.logo {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 800;
  color: #fff;
  background: linear-gradient(135deg, #10B981, #0ea5e9);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  text-decoration: none;
  letter-spacing: -0.02em;
  flex-shrink: 0;
}

.main-nav ul {
  display: flex;
  gap: 2.5rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.main-nav a {
  color: var(--color-text-muted);
  font-weight: 500;
  font-size: 0.95rem;
  position: relative;
  transition: color 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  text-decoration: none;
}

.main-nav a:hover,
.main-nav a[aria-current="page"] {
  color: #fff;
}

.main-nav a::after {
  content: '';
  position: absolute;
  bottom: -6px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-primary);
  transition: width 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: 2px;
  box-shadow: 0 0 10px var(--color-primary);
}

.main-nav a:hover::after,
.main-nav a[aria-current="page"]::after {
  width: 100%;
}

.search-form {
  display: flex;
  background: rgba(255, 255, 255, 0.05);
  border-radius: 20px;
  padding: 0.35rem 0.75rem;
  border: 1px solid rgba(255,255,255,0.08);
  transition: background 0.2s, border-color 0.2s;
}

.search-form:focus-within {
  background: rgba(255, 255, 255, 0.1);
  border-color: var(--color-primary);
}

.search-form input {
  background: transparent;
  border: none;
  color: #fff;
  padding: 0.25rem 0.5rem;
  outline: none;
  width: 120px;
  transition: width 0.4s;
  font-family: var(--font-body);
  font-size: 0.875rem;
}

.search-form input:focus {
  width: 180px;
}

.search-form input::placeholder {
  color: var(--color-text-muted);
}

.search-form button {
  background: transparent;
  border: none;
  color: var(--color-text-muted);
  cursor: pointer;
  transition: color 0.2s;
  font-size: 1rem;
}

.search-form button:hover {
  color: var(--color-primary);
}

/* Mobile menu button */
.mobile-menu-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 5px;
  z-index: 1001;
}

.mobile-menu-btn span {
  display: block;
  width: 24px;
  height: 2px;
  background: #fff;
  border-radius: 2px;
  transition: all 0.3s;
}

/* Responsive */
@media (max-width: 768px) {
  .site-header {
    top: 0.5rem;
    width: calc(100% - 1rem);
    border-radius: 20px;
    padding: 0.5rem 1rem;
  }

  .mobile-menu-btn {
    display: flex;
  }

  .main-nav {
    display: none;
    position: absolute;
    top: calc(100% + 0.5rem);
    left: 0;
    right: 0;
    background: rgba(11, 15, 25, 0.95);
    backdrop-filter: blur(20px);
    border-radius: 16px;
    border: 1px solid rgba(255,255,255,0.08);
    padding: 1rem;
  }

  .main-nav.active {
    display: block;
  }

  .main-nav ul {
    flex-direction: column;
    gap: 0;
  }

  .main-nav li {
    border-bottom: 1px solid rgba(255,255,255,0.05);
  }

  .main-nav li:last-child {
    border-bottom: none;
  }

  .main-nav a {
    display: block;
    padding: 0.75rem 1rem;
    font-size: 1rem;
  }

  .search-form {
    display: none;
  }
}

.theme-toggle {
  background: transparent;
  border: none;
  color: var(--color-text-main);
  font-size: 1.25rem;
  cursor: pointer;
  padding: 0.5rem;
  margin-left: 1rem;
  border-radius: 50%;
  transition: transform var(--transition-fast), background 0.2s;
  display: flex;
  align-items: center;
  justify-content: center;
}
.theme-toggle:hover {
  transform: scale(1.1);
  background: rgba(255, 255, 255, 0.1);
}
[data-theme="light"] .theme-toggle:hover {
  background: rgba(0, 0, 0, 0.05);
}

@media (max-width: 768px) {
  .theme-toggle {
    margin-left: auto;
    margin-right: 1rem;
  }
}