/* ================================================
   GitHub 官方风格导航栏
   ================================================ */

.github-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: 60px;
  background: var(--header-bg);
  border-bottom: 1px solid var(--header-border);
}

.header-container {
  max-width: 100%;
  margin: 0 auto;
  padding: 0 var(--space-4);
  height: 100%;
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

/* 左侧 */
.header-left {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* 汉堡菜单 */
.hamburger-btn {
  width: 40px;
  height: 40px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  background: transparent;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  padding: 0;
  transition: background 0.15s;
}

.hamburger-btn:hover {
  background: var(--header-hover);
}

.hamburger-btn span {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 1px;
  transition: all 0.25s ease;
  transform-origin: center;
}

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

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

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

/* GitHub Logo */
.header-github-link {
  color: var(--text-primary);
  transition: opacity 0.15s;
}

.header-github-link:hover {
  opacity: 0.8;
}

/* 中间品牌 */
.header-center {
  flex: 1;
  display: flex;
  justify-content: center;
}

.brand-link {
  font-family: var(--font-mono);
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: 0.1em;
  transition: opacity 0.15s;
}

.brand-link:hover {
  opacity: 0.8;
}

/* 右侧 */
.header-right {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* 搜索框 */
.header-search {
  position: relative;
  display: none;
}

.search-input {
  width: 220px;
  height: 32px;
  padding: 0 var(--space-3);
  background: var(--header-hover);
  border: 1px solid var(--header-border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 0.875rem;
  outline: none;
  transition: all 0.15s;
}

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

.search-input:focus {
  background: var(--header-bg);
  border-color: var(--accent-primary);
  width: 260px;
}

/* 图标按钮 */
.icon-btn {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s;
}

.icon-btn:hover {
  background: var(--header-hover);
  color: var(--text-primary);
}

/* 主题按钮 */
.theme-btn {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s;
}

.theme-btn:hover {
  background: var(--header-hover);
  color: var(--text-primary);
}

.theme-btn svg {
  display: none;
}

.theme-btn .icon-sun { display: block; }
[data-theme="dark"] .theme-btn .icon-sun { display: none; }
[data-theme="dark"] .theme-btn .icon-moon { display: block; }
[data-theme="light"] .theme-btn .icon-moon { display: none; }

/* 主题下拉菜单 */
.theme-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 120px;
  background: var(--header-bg);
  border: 1px solid var(--header-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-xl);
  padding: var(--space-1);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  transition: all 0.15s;
  z-index: 100;
}

.theme-dropdown.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.theme-option {
  width: 100%;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.875rem;
  cursor: pointer;
  transition: all 0.15s;
}

.theme-option:hover {
  background: var(--header-hover);
  color: var(--text-primary);
}

.theme-option.active {
  background: var(--accent-primary);
  color: white;
}

/* 头像 */
.header-avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  border: 1px solid var(--header-border);
  object-fit: cover;
  cursor: pointer;
  transition: border-color 0.15s;
}

.header-avatar:hover {
  border-color: var(--text-secondary);
}

/* ===== 侧边导航 ===== */
.nav-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 1001;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.2s, visibility 0.2s;
}

.nav-overlay.show {
  opacity: 1;
  visibility: visible;
}

.nav-sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: 300px;
  height: 100vh;
  background: var(--header-bg);
  border-right: 1px solid var(--header-border);
  z-index: 1002;
  display: flex;
  flex-direction: column;
  transform: translateX(-100%);
  transition: transform 0.25s ease;
}

.nav-sidebar.show {
  transform: translateX(0);
}

.nav-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4);
  border-bottom: 1px solid var(--header-border);
}

.nav-title {
  font-weight: 600;
  font-size: 1rem;
}

.nav-close {
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s;
}

.nav-close:hover {
  background: var(--header-hover);
  color: var(--text-primary);
}

.nav-user {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-4);
  border-bottom: 1px solid var(--header-border);
}

.nav-user-info {
  flex: 1;
}

.nav-user-name {
  font-weight: 600;
  font-size: 0.9375rem;
  color: var(--text-primary);
}

.nav-user-id {
  font-size: 0.8125rem;
  color: var(--text-tertiary);
}

.nav-links {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-2);
}

.nav-section {
  margin-bottom: var(--space-4);
}

.nav-section-title {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: var(--space-2) var(--space-3);
}

.nav-link {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-2) var(--space-3);
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9375rem;
  border-radius: var(--radius-md);
  transition: all 0.15s;
}

.nav-link:hover {
  background: var(--header-hover);
  color: var(--text-primary);
}

.nav-link svg {
  flex-shrink: 0;
}

.nav-footer {
  padding: var(--space-3);
  border-top: 1px solid var(--header-border);
}

/* 主题变量 */
[data-theme="dark"] {
  --header-bg: #161b22;
  --header-border: rgba(255, 255, 255, 0.1);
  --header-hover: rgba(255, 255, 255, 0.05);
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-tertiary: #6e7681;
}

[data-theme="light"] {
  --header-bg: #ffffff;
  --header-border: #d0d7de;
  --header-hover: #f6f8fa;
  --text-primary: #1f2328;
  --text-secondary: #656d76;
  --text-tertiary: #8c959f;
}

/* 响应式 */
@media (min-width: 768px) {
  .header-search {
    display: block;
  }
}

@media (max-width: 768px) {
  .header-center {
    flex: 1;
    justify-content: flex-start;
    margin-left: var(--space-2);
  }

  .brand-link {
    font-size: 1rem;
  }

  .nav-sidebar {
    width: 100%;
    max-width: 320px;
  }
}