/* ============================================
   SITE HEADER
   ============================================ */

.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: rgba(10, 10, 10, 0.85);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--color-border);
    z-index: var(--z-header);
    transition: background var(--transition-base);
}

[data-theme="light"] .site-header {
    background: rgba(245, 245, 245, 0.85);
}

.site-header__inner {
    display: flex;
    align-items: center;
    height: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-md);
    gap: var(--space-lg);
}

/* Logo */

.site-logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    text-decoration: none;
    color: var(--color-text);
    flex-shrink: 0;
}

.site-logo__mark {
    width: 32px;
    height: 32px;
    background: var(--color-accent);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: var(--weight-bold);
    color: #fff;
    font-size: var(--text-lg);
}

.site-logo__text {
    font-size: var(--text-lg);
    font-weight: var(--weight-bold);
    letter-spacing: -0.02em;
}

.site-logo__text span {
    color: var(--color-accent);
}

/* Main nav */

.main-nav {
    display: none;
    align-items: center;
    gap: var(--space-xs);
}

.main-nav__link {
    padding: 0.5em 0.9em;
    font-size: var(--text-sm);
    font-weight: var(--weight-medium);
    color: var(--color-text-secondary);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
    position: relative;
}

.main-nav__link:hover {
    color: var(--color-text);
    background: var(--color-accent-subtle);
}

.main-nav__link--active {
    color: var(--color-accent);
}

/* Header search */

.header-search {
    flex: 1;
    max-width: 360px;
    margin-left: auto;
    display: none;
}

.header-search .input {
    height: 36px;
    font-size: var(--text-sm);
    background: var(--color-bg-elevated);
    border-color: transparent;
}

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

/* Header actions */

.header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    margin-left: auto;
}

/* Theme toggle */

.theme-toggle {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-sm);
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
}

.theme-toggle:hover {
    color: var(--color-text);
    background: var(--color-accent-subtle);
}

.theme-toggle__icon--light {
    display: none;
}

[data-theme="light"] .theme-toggle__icon--dark {
    display: none;
}

[data-theme="light"] .theme-toggle__icon--light {
    display: block;
}

/* Mobile menu button */

.mobile-menu-btn {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-secondary);
    border-radius: var(--radius-sm);
}

.mobile-menu-btn:hover {
    color: var(--color-text);
}

.hamburger {
    width: 20px;
    height: 14px;
    position: relative;
}

.hamburger span {
    display: block;
    width: 100%;
    height: 2px;
    background: currentColor;
    border-radius: 1px;
    position: absolute;
    left: 0;
    transition: all var(--transition-fast);
}

.hamburger span:nth-child(1) { top: 0; }
.hamburger span:nth-child(2) { top: 6px; }
.hamburger span:nth-child(3) { top: 12px; }

.mobile-menu-btn[aria-expanded="true"] .hamburger span:nth-child(1) {
    top: 6px;
    transform: rotate(45deg);
}

.mobile-menu-btn[aria-expanded="true"] .hamburger span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-btn[aria-expanded="true"] .hamburger span:nth-child(3) {
    top: 6px;
    transform: rotate(-45deg);
}

/* Mobile nav panel */

.mobile-nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--color-bg);
    z-index: var(--z-overlay);
    padding: var(--space-xl) var(--space-md);
    transform: translateX(100%);
    transition: transform var(--transition-base);
    overflow-y: auto;
}

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

.mobile-nav__link {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-md) 0;
    font-size: var(--text-lg);
    font-weight: var(--weight-medium);
    color: var(--color-text-secondary);
    border-bottom: 1px solid var(--color-border);
    transition: color var(--transition-fast);
}

.mobile-nav__link:hover,
.mobile-nav__link--active {
    color: var(--color-text);
}

.mobile-nav__link-icon {
    width: 20px;
    text-align: center;
    color: var(--color-accent);
}

.mobile-nav__search {
    margin-bottom: var(--space-xl);
}

/* ============================================
   RESPONSIVE
   ============================================ */

@media (min-width: 768px) {
    .main-nav {
        display: flex;
    }

    .header-search {
        display: block;
    }

    .mobile-menu-btn {
        display: none;
    }

    .header-actions {
        margin-left: 0;
    }
}